I have been using Vista since the beta was out. I used it full time since the release of RC1. BTW - I am using the Vista Ultimate on my laptop at home and Vista Enterprise at work.
Pros:
1. Switch user mode in a domain. XP did not have switch user capabilities.
2. Bitlocker - great for protecting laptop data. Since I deal with a lot of sensitive data at work, bitlocker will allow me to secure my laptop.
3. Aero - nice looking screen
4. Icon and font scaling. Hold down your ctrl button while scrolling the wheel will scale your icons and fonts. Much better than Windows XP.
5. Better Search feature
6. Firewall - now does egressing as well as ingressing filtering!
7. Built in spyware program
8. IE7 built in. I love the fact that ActiveX is much more secure. ActiveX can not longer directly interact with the OS.
8. Much better help pages.
Cons:
1. Uses lots of memory. I think the realistic minimum is 2GB. I have 4 GB. (BTW - if you are running the 32bit version, you will not be able to use all 4 GB). I am actually debating on switching over to the 64bit version and going with 8GB of memory.
2. Slow. The interface seems slower than Windows XP.
3. UAC - while good in some cases, it can be a real annoyance. I have UAC disabled on my computer. With UAC enabled, you can't do some simple stuff. For example, if you open up a command prompt, you can't do a simple command (such as IPCONFIG /RENEW).
4. The start menu sucks. I like XP's cascading menu.
5. Some of MS domain tools (and Exchange tools) do not work with Vista unless you hack it.
My office is doing a complete computer replacement this summer. We are going to switch to Vista Enterprise and Office 2007. However, I am not recommending that people upgrade to Vista at this moment unless they are purchasing a new machine, and they use pretty standard software.
BTW - if some of your software aren't running correctly, have you tried running the program in compatibility mode and also "administrator" mode? I have had few driver issues - but my hardware are pretty standard stuff.
Minh