Update: Another day after this was written, and we've upgraded a number of our main production Dell Windows 8.1 systems to 10.
The process was remarkably smooth, and kudos to Microsoft for how well everything migrated.  It is now our belief that more of the issues noted below are specific to Lenovo hardware.

This will be a living document as we find and add new bugs, and those that are (hopefully) fixed by the rapid release cycle intended for Windows 10.  Feel free to submit bugs you've found in the comments.

The change at Microsoft since Satya Nadella took over Microsoft has been swift, and impressive. While there are still some questionable decisions and priorities the overall direction, mood and product quality have taken a significant turn for the better.

Few projects show off this new Microsoft as much as Windows 10. In contrast to the black hole that was the Windows 8 development process - and the subsequent trouncing it received from the press and customers - Windows 10 was from the start a project run in a starkly open manner, and the right goals.  For that, and what has resulted, it is being almost universally praised.

Through Twitter, forums and most importantly the Insiders Program, Microsoft showed they actually - finally - give a damn about their most visible and important product, and what those of us who use and support it might actually think about it and want. Profound.

We've been testing Windows 10 since the earliest of builds - which were ludicrously buggy and unpolished - but still showed a great direction.  It's been enjoyable to watch it mature and develop into what's going to be a fantastic OS.

The problem? It's not going to be a fantastic OS until October; when it was originally planned to be released. Instead, in order to follow the current trend of release fast and often, and to hit the back to school season, it has been shoveled out the door to consumers. But oh my, is this thing overflowing with bugs. It's full of promise, but painfully quirky.  More importantly, bugs that have persisted in Windows for literally years; and through multiple full versions; solider on untouched.  

While it's exciting to see this released to the world, and it's a big step up from Windows 8, we fear that by rushing this thing out Microsoft has proven once again they can't make something that works right the first time. It also shows how - still - the PC vendors are the weak link in this entire thing. While an improvement over previous generations of Windows, it's still a frustrating disaster trying to get up to date drivers, and often endlessly searching horrible support sites for bits and pieces that may or may not work.  It's both sad and ridiculous how badly Lenovo and the likes can continue to screw this stuff up.

The Reality

Here's the bugs we've found running it on three systems over the course of a few days since "the big day."  This is using the July 29 10240 build - with all the patches - on modern Core i5 and i7 Ultrabooks and Convertibles. 

Allegedly a Service Release 1 is coming within the next week. We can only hope, because, wow, just wow.  Put this thing back in the oven.

The White Screens and Missing Apps

These happen very frequently when resuming from sleep.  It appears to be bugs with the WWAHost.exe process, which is the actual host process that all Universal (formerly Metro/Modern) Apps run under.  From our experience many times that process just crashes on sleep or resume, and takes down all the Apps with it.  Other times WIndows.UI.Xaml.Dll - XAML being one of the fundamental building blocks of Universal Apps - appears to crash, and creates what we've dubbed "The White Screens."  That is, the Universal App appears to be running, and still doing things, just the entire presentation layer is converted into one big white, unusable box.  The only solution is to restart the App.  This happens constantly in Edge, Mail and the Store.

I Can't Get No Sleep

There is a 205 page thread on the site EightForums discussing thousands of people - us included - who to this day cannot ever get Windows 8.x to reliably idle to sleep.  This same fate befell Windows 7 before it, and I dare you to find more than a handful of Windows users who honestly believe their laptop will always sleep and wake up reliably.  Apple has consistently nailed this (and power management in general) across their devices, but here we are on day one of "The Best Windows Ever" and a nearly new laptop sits wide awake until the battery nearly dies.  There's a "known issue" with Cortana - one of the key features of the new OS - already causing this.  The "SRVNET" networking glitch that's existed since Windows 7 - still going.  Who knows what else!

This is flat out ridiculous BS.  PLEASE FIX THIS FOR GOOD, MICROSOFT.

Touchy Touch Pad

Another area that Apple understands is SO important to the overall sense of polish, and ongoing satisfaction with the system is their exceptional touch pads.  While this is mostly the computer manufacturer's fault, this just needs to get fixed once and for all.  Microsoft needs to take control of these crucial drivers and experiences, and refuse to allow the bundling of the profoundly awful Synaptics software, and the like.

Not only that but they removed many of the touch gestures, so in programs like Edge we now can't swipe back and forth around web pages and apps, and the multi-finger touch pad equivalents appear to be gone as well, supposedly unless you have the new "Precision Touchpads" - available in the Surfaces and one Dell XPS 13 model.  Bonus: The Synaptics drivers (freshly delivered from Microsoft Update) appear to crash a lot, and we then further lose the ability to even scroll with the touch pad until reboot.

Universally Different

Let's give credit where its due: the Universal Apps are, uh, universally much more attractive and functional than the ugly Fisher Price UI equivalents that were Windows 8 Apps.  This almost HAS to go better for Microsoft this round, as it fits the look and feel of other platforms, and should attract developers.  However, the first party Apps Microsoft has shipped are completely all over the map and rife with inconsistency.  Some have black UI, some have white, some have shadows, some don't. The buttons are all in different places, and different looking, or don't have buttons at all. Some are dots, some are gears. Cut and Paste doesn't work very reliably (seriously). Even text selection is randomly different in the Mail app, than it is everywhere else.  On it goes. 

Plus, we seem to get this weird hangover of Windows 8 where randomly something will slide awkwardly from the right hand side.  They're apparently still trying to target touch friendly devices, but we miss all the wonderful edge swiping UI in most other modern OSs, including when using Windows 10 Mobile.  Windows 8's UI was completely non-discoverable.  Now it's just partially non-discoverable. 

Even the Shell/Windows Explorer has about six different UIs and shows just how completely mashed together this thing is.  You even sometimes see windows come up first drawing the old school Windows GUI, then quickly covering it up with the newer style. It just feels so unpolished. Last, but not least, File Explorer looks like it's frozen in time from Windows XP, with horrendous icons, despite a barrage of negative feedback during the course of the Insider Program.

Groove to the CPU Fan

On the Lenovo laptops - no matter what we do with audio drivers - Groove Music takes 30-40% CPU.  Constantly.  Even not playing music.  Generally this means we get to enjoy the fan, more than the music.  It's not indexing or doing anything interesting.  It can even just be sitting doing nothing.

The Edge of Frustration

The new Edge browser is fast and a huge step up from Internet Explorer, obviously, but it in addition to only being half done yet: no extensions, etc., it also has some glaring problems. We still find it slow at loading large sites where it seems to struggle to load the graphics and draw the pages if you scroll while it's loading.  Chrome can load the same site without this problem.

The most glaring problem we found though is downloading files.  On all of our systems, if you download a program executable, it will happily download (and annoyingly without any prompt or ability to choose where to put it), then present a Run button.  Clicking this effectively locks up the browser, and the downloaded program isn't run. 

The problem is it throws up a User Account Control prompt that gets stuck in a layer somewhere that won't interact with the user.  The browser is then stuck for eternity waiting for a prompt that' can't be clicked and won't timeout.  The only solution is to kill the process.

How did this honestly get released with such a showstopper?

OneHell

As noted pretty much everywhere online, OneDrive is a huge step backward.  It lost placeholder support from Windows 8, and to this day the sync engine is terrible and constantly gets stuck.  Microsoft is supposed to be creating a new sync engine and single client for OneDrive and OneDrive for Business.  It can't come soon enough as this icon is all you'll ever see.

Overall we found the experience to be significantly worse on Lenovo hardware than on Dell, which seemed to upgrade and run smoother, but the quirks are just rampant the more you use this.

e love you Windows 10, but please get better, and fast.  To our business customers - wait until October.