after using it i'm pretty happy with the upgrade especially considering the price. the new sound library is cool but not really all that much over 7.2, lots of these instruments they're advertising are exactly the same. also, they had originally posted on their website that there was a new pitch correction tool ala melodyne but this isn't really true, and there's no beat detective feature, still.
although they didnt deliver on any of that stuff, there is some real improvement. like formant said ultrabeat got a ton of new sounds and a step sequencer. the program is way faster on my g5. the library lets you tag, search, and scroll through instrument presets which is amazing, its a lot like mediabay in cubase 4 except it works well. the sample accurate editing in arrange is nice also. the compressor also sounds way better now, they added some vintage modeling to it so it can really thicken up your sounds.
just make sure you have plenty of hd space, the full install i think is around 35 gigs.