I've been dual booting XP and Vista for about a week now, and haven't gotten down to using Vista other than on a few occasions. I cannot say whether I like or dislike it.
But some of you are overlooking some of the biggest differences that we got from Windows 98 to XP, one being stability. Other huge differences that we got were Task Manager, System Restore, Firewall and a vastly improved GUI to mention a few.
Again, I don't know enough about Vista to give my opinion on whether it is worth it or not, but I certainly hope that it will bring as much to the table as XP brought.