I played Project M for the second time today. The thing that currently bothers me the most is that it's way too easy to accidentally fsmash in a couple different ways. A lot of the time, I want to dash back, then turn around and dash attack, but I can't do this without fsmashing instead unless I wait a long time after the pivot, which is really inconvenient. I also accidentally fsmashed often when trying to ftilt, although I'm guessing this isn't a huge problem and my lack of familiarity with the game is probably to blame.
There are a few other things that bother me, but since they mostly pertain to a character that has barely been worked on, I won't rant about those.