There are a lot of new features in this update: improved scoring, a free budget version of Halion Orchestra to experiment with, LoopMash and a loop programmer tool called Beat It!, which works with the new Groove Agent drum sample player.
Vocalists will be pleased to see pitch correction and much improved vocal-editing tools, while there's also a sampled reverb tool called Reverence that sounds excellent.
There are still some issues to sort out, though. Our main gripe is that you're often left in window hell, with 10 to 20 to manage at once. Even on a giant monitor, you won't be able to see more than a few simultaneously. We think that some form of accessible window manager would make Cubase much easier to work with.
That said, it's still among the best sequencers around, and it can do pretty much whatever you want, even if it takes a while to get there. Most importantly, Cubase 5 makes great music, producing a rich, lush sound that's utterly professional.