The art style is maintained (and most of the clothing items) but is pretty significantly improved. There seems to be a lot more band/song scripting going on, as well. The new UI is better - even more streamlined - but I kinda wish they'd stolen GH's fretboard customisation.
The play flow improvements are worth the money by themselves. Making setlists, organising music and playing in groups is way easier and involves a lot less fucking around with profiles and instruments. You can even play 3 singers + 4 instruments, which is pretty outrageous. The quick-play options are there from Band Hero, but I haven't seen the in-song song-change option, which is a shame. The whole band world tour idea is toast - or at least spread over the whole game, so there's no modes to go in and out of. In short, flow from grouping to getting into a song you actually like is easier, which is a big success.
Importing (at least for RB1) was totally seamless, but RB2 doesn't seem to have the export option yet. Not being able to get the RBN songs in Australia continues to be fucking annoying. Hilariously I'm #37 in the world at Godzilla at the moment...
