I am one of those guys that installs beta versions of Windows the day they come out. I believe it is referred to as 'bleeding edge' appropriately. I have suffered for the last 2 years with a buggy version of Vista, that no amount of tips, registry edits, updates, service packs, or even reinstalls seemed to fix.
For example, my PC absolutely hated Microsoft Office. 2003 or 2007, didn't matter, although 2007 was so bad it was unusable. I know these are good products, I use them on other computers with no problems. The laptop I have, which came with Vista Home Premium, has had no problems whatsoever. But on my PC, Office was so bad I didn't even use it. If I tried to open any type of document - Word, Excel, an Access database - it would launch into the Microsoft Office Installer and begin an endless cycle of events. Outlook was the worst offender, it would launch the installer for EVERY MESSAGE!
There were other strange issues, as well. No updates for Visual Studio or SQL Server would install. So I've had a growing list of these updates in my Windows Update list for the past 18 months at least. I am a Microsoft guy, I have friends on the SQL Server development team, blah blah blah, so to not be able to resolve these issues was incredibly frustrating. I had actually started to believe it was a hardware issue with my particular PC, which is ridiculous. However, it was better to believe that than to think that I couldn't fix my own PC. And trying to trick myself to believe that was particularly painful.
So anyway, because I am a bleeding edge kind of guy, I downloaded and installed Windows 7 beta the day it was released. And to my suprise, it is fantastic. Honestly, I don't know why it isn't called Vista SP2 other than Microsoft gets to charge for new licenses this way. Sorry guys, had to say it. I don't know what is going on specifically different under the hood, but it sure seems like a tidied up version of Vista. And it doesn't seem to have more new features than say XP sp2 did.
But I can say that it is remarkably stable - I haven't rebooted at all yet - and it fixed all of my unusual issues. I have had only 1 application that did not survive the upgrade, and that was a client's Cisco VPN. But I run a Virtual XP machine and use that to connect, and it runs beautifully.
And the features that Microsoft did improve upon are all very nice. They work so well, and are on top of the Vista Aero interface, it makes you wonder why they did release Vista the way it was. Again, sorry... But I have to admit that so far, Windows 7 is quite impressive. There are a few things Microsoft did, like moving familiar items around, renaming them, etc., that drive you batty at first - just like with all new Windows releases - but at least there seems to be a logical rhyme and reason to them. They have even updated some of the core accessories that seemed like they hadn't changed since Windows 3.1 - like the Calculator now does date math and statistics.
On top of this, the installation process was incredibly painless. I did an upgrade, which is usually a bad idea time-wise, but even with 800,000+ files to convert the entire installation took about 90 minutes. I would suspect a clean install would have taken about 25 minutes, which is on par with some of the better Linux packages.
So my hat goes off to Microsoft for a job well done. I believe that Microsoft is targeting a 3rd quarter release of Windows 7, and I see no reason why that would not happen. This is by far the most polished beta OS they have released. I also believe that many businesses, that have been slow to transition to Vista - or have avoided Vista altogether - will make the switch to 7. Primarily because it's the Vista that should have been.