Resource Hog
I agree about that point (but I haven't really used the "final" Vista)
While running RC2 on my laptop (with 1GB RAM and a Turion64 2GHz processor) I thought it ran just as fast as XP did, however, when I ran Eclipse, jEdit, MySQL, Apache, Apache Tomcat etc. I noticed things starting to slow down.
There were no real lockups or crashes, but it was considerably slower than when running XP.
I put it down to beta-syndrome and presumed that things would chug along nicely once Vista was properly released.
It seems that 1GB is not enough - perhaps you could do with 1.5 or even 2GB RAM.
Surely MS should never have recommended 1GB system memory for Ultimate...