Cons
Not enough Rin (not enough non-Miku in general)
Songs (so far, possibly altogether) are all dancing stages (PV's and songs no longer tell stories)
No loading images to collect
Costume unlocks are completely random (or seem to be)
Story is basic
Opening movie is boring
Miku Room type interaction is a lot simpler (no head rubbing/minigames that I can see, or an actual Miku room itself; seems to be the default menu now, and you can't decorate it yourself, they'll put stuff you give them onto the same shelves)
The new Clear/Clear+ isn't any better than the old Standard/Great/Excellent/Perfect system
The new scoring system may prevent you from using your favourite modules, or force you to use accessories you don't want to, in order to clear a song (failed a song because of the module setup I used; don't know if that'll be common on higher difficulties/harder songs)