The only problem I have, is the lack of 0 cost abilities (for TP building etc.)
Because Honestly, going back to old AA bored the living P*ss out of me.
I was "almost" ready to go back to Quit status, until I hit Lv30, and had all 3 of them on my bar.
Suddenly the game felt fun and every new ability felt like i was progressing, and getting to have more fun.
I could be wrong, but It "seemed" like the 0 cost abilities were removed. (Would have to triple check again to be sure, as this just came to mind.)