I just got Vista for two reasons. Mainly because through a combo at Newegg it was quite reasonable in price. The other being I wanted to use more memory than my XP pro x86 will allow. I got Vista Ultimate x64.
Unless you are like me and really want more memory and currently only have a 32bit OS, then yes, Vista is worth it. It is stable, fast and given enough ram works wonderfully.
If you don't want more than 3.2GB of usable ram (with a x86 OS), or you already have XP x64, then wait for 7.
Right now Vista is using 1286MB of ram and this with many services and such shut down. Nothing I have open except this page. It is only using around 0-1% of my cpu as I write this.
Some games, especially newer ones are running better and more stable on Vista.
I like it and I'm glad I got it. I haven't had any issues to speak of and it does have some nice features that XP lacked.
I would recommend no less than 4GB of memory and really 6 or more is better, especially if using ram hungry programs. Vista will use what you have very effectively. I have 8GB and that seems to be plenty, for my needs, mainly gaming. FSX runs very well on Vista. No problems that I have seen.
Oh yeah, My Windows folder is taking up 18.8GB of space on my HDD

It has only been installed for 2 weeks and nothing added except Windows updates and hardware drivers. I'm glad I made my C: partition 97.6GB
Hope this helps
