The main issues I was having with Vista was very poor battery life, poor Wifi connections (dropping connections and just refusing to reconnect) and many failures with the sleep functionality (an essential feature for a laptop). I was actually so fed up with Vista that most of the time I preferred to use my private MacBook..
I decided to do an upgrade, because I didn't expect proper driver support, it seemed a safer option. The upgrade went smooth, but extremely slow. I guess it took 4 hours or so to complete. Immediately after the upgrade I installed the MP3 patch and a Beta Antivirus application. All settings and applications migrated perfectly, including the fingerprint reader and other drivers. This is actually very interesting, because I still have all the same drivers installed as when I was still running Vista... Microsoft, the story that the drivers are the cause of most Vista problems is for that reason not TRUE!
In the first days I experienced some very weird behavior with Office 2007 application, they were extremely, extremely, extremely slow to start, but like a miracle this resolved itself after starting them a number of times. Now they are fine. I still do have some minor issues, like the 10 year old bug that Outlook doesn't close properly. Pressing the window close X doesn't properly close, but File-Exit does. I also have some issues with TweetDeck (Adobe Air) it has a problem when I minimize and go into sleep mode. Now a month later I run everything I need, actually not that much, without real problems. I haven't had any blue screens and only a few times Sleep - Wake up problems, like a drained battery due to refuse to go to sleep.
The key requirements for a laptop are definitely better with Windows 7. Battery life is about 30% better (no scientific test), I haven't had a single Wifi connection problem and I now confidently close the lid to go into sleep mode. This all resulting me to use my Windows machine more frequently again, but still prefer my Mac though...
What would I still like to see improved? Microsoft you can do it, if you really want it! Battery life is still not good enough, Wake up from sleep and booting is still too slow and further you need to improve some user interface behavior. For instance you need an additional click when starting something from the start menu and it took me a week to figure out how to start a second instance of a pinned task bar application.
Microsoft, you did a good job on improving the basics and fixing many Vista bugs, but I miss any added value in Windows 7. It's a good Vista SP3 or at best a $20 upgrade for the DVD. I really hope you take this in consideration when deciding on pricing.