Nothing really wrong with Vista IMO, it's all down to who's using the machine. Just as many of our customers manage to stuff their XP install's up as Vista installs
If anyone remembers nobody wanted XP when it first came out - "my mate says it's rubbish" ect, then the same thing happened with Vista when that was released. At least with Vista if an application falls over just the application hangs 99% of the time, unlike XP which likes to crash explorer as well for good measure! I wouldn't say Vista was especially slow either, RAM is cheap these days and is the main factor that improves things. There's no excuse to have any less than 4Gb now, and anyone trying to run Vista on a single core CPU shouldn't expect it to be snappy.
I agree that 7 is how Vista should be, but there's no real reason if you have an existing machine with Vista to goto the expense of upgrading IMO