One month is, Windows 7 is definitely more stable than Vista, and I suspect that it's the most stable version of Windows ever, but I can't say that with certaintly since I've never used XP. However, I probably try a dozen new freeware programs a day, and not one has succeeded in crashing Wondows 7.
However, if you have no problems with Vista, there's also no compelling reason to upgrade to 7 if for no other reason than I've had to find a new program to do backups (which I haven't needed and the program I found was a simple upgrade of the one I had). Because my backup program is the single most important program I hope I never have to use again for restoration purposes.
Otherwise, I haven't found anything that Windows 7 does that Vista didn't do, nor have I found any programs that won't run that ran under Vista. All I can say is that 7 has a subtle feeling of smoothness (but no meaningful increase in speed) which translates into reduced stress – when there's a rare glitch, I just sit for a second and Windows recovers (if in fact it was recovering at all since hangups can be caused by any number of things).
So I wish I had something dramatic to report, but for ordinary users, drama in the operating system is something they can probably do without – And Windows 7 certainly lessens the drama. I don't believe I've lost anyting since I've upgraded to Wondows 7, and that includes restore points. However, I did have to find them initially as they are another example of Microsoft moving something for seemingly no reason.