Yeah, I have to agree; some of the changes they made were not for the better. In my case, my criticisms are for:
1: the chase sequences being sped up a little too much
2: knocking the opponent into a vanish trap no longer allowing for the continuation of chase sequences
3: dodging no longer replenishing jumps (making it harder to stay in the air)
4: the removal of invincibility after crashing into a barrier (wall rush damage was also reduced from 50% to 25%)
5: EX cores not filling up the meter as much,
6: less EX force being generated from attacks,
7: the EX Revenge feature that sacrifices both the ability to regenerate health and the ability to use an EX Burst
8: the Assistant deducting EX force and the ability to knock you out of EX Mode prematurely
9: Arcade Mode no longer awarding PP
10: not being able to quit Arcade Mode without entering a defeat screen
11: not being able to transfer any PP won in the original Dissidia into the save data (they transfer items that were already bought from the PP catalog, but not remaining un-spent PP), which makes it harder to buy things like alternate costumes (I was able to unlock an alternate costume really quickly in the original, but in 012, it takes a lot more time)

I hope they remake this game in a few years time, albeit with more characters and storyline changes to include these new characters, and have the feel of the original game rather than 012. I have a feeling they would call it Dissidia Final Fantasy 012 and 013 [duodecim et tredecim], because tredecim is Latin for "thirteen."