I'll preface this by saying: A) I'm an okay player at project M. I normally get decently far at the tournaments I've gone to, but I have no illusions on the huge gap between me and the people who actually win said tournaments. I also admittedly haven't gone to a tournament since moving to California 4 months ago, and I've mostly only played online since. B) That while I loved Melee, I was a complete noob until brawl mods (Brawl+, Brawl-, PM), and as such, I don't feel that I have a particularly heavy bias towards Melee. I enjoy PM far more, simply because of the variety of viable characters.
EDIT: I have NO illusions... whoops
I think there is something to be said about the skill required to do something. There is a notable difference for me in the satisfaction of succeeding with a tactic requiring skill vs the satisfaction of succeeding with something that's easily done. When something takes skill via tech skill, careful planning and trapping, and/or baiting and quickly punishing, not only is it more satisfying to get the hit, but the pressure/fear of losing has a much more significant impact on your ability to do said tactic. And I LIKE that there's a huge mental aspect to this game. And on the flip side there is a notable difference for me in defeating a tactic that takes skill compared to defeating a tactic that's easily done. Really, if something is easily done, like spamming an attack, I'm frustrated if works at all.
Now, I don't think PM has this problem for the most part, but I can think of a few things off hand that at least SEEM to be fairly effective despite not being difficult. Both Mario's fireball and Ivysaur's razor leaf seem to effortlessly win the neutral game and/or force the opposing character into a poor position. Compare this to the ever hated Falco's laser. While Falco's neutral game is absurd BECAUSE of his laser, it does take some skill to time the fast fall and laser to get it at the right height, and the inputs required are relatively fast paced. Compare this to short hop/full hop fireball or short hop razor leaf, and while you see you get similar results (doing well in neutral, albeit not AS well), the satisfaction for both players in the match is substantially less (regardless of whether or not the easy tactic succeeds). Also, if a Falco player isn't able to keep his calm, and starts breaking under the pressure, then his lasers get sloppy. I don't really feel like there is concern for that happening for someone using either razor leaf or mario's fireball.
Now, I don't hate these characters, in fact I personally think Ivysaur is (otherwise) nearly perfectly designed. (I don't really use Mario so I'm more or less apathetic about him). Now, I don't know what the alternative is, but I will say that Wolf's laser takes skill to use and din's fire, and snake's projectiles take lots of understanding and planning to use, and I thoroughly enjoy both using and facing these characters.
But truth be told, I get a little annoyed when I see fireballs or a razor leaf coming my way. Even when I can still win the match, and even when the person is clearly better than me and I'd have no hope either way. And it's not even fair to blame the Ivy or Mario user, since they SHOULD use the tools they were given. And many of them could still pull off the win just as well if their tools took more effort, but the feeling during and after the match would be different for me, and I think them as well. (I use Ivy as a secondary, so I'm somewhat on both sides of this).
And so, to an extent, I can relate to the idea that in PM some things are just straight good, and whereas in Melee you had to work for it, and that moves being good without effort can sometimes be a bad thing.
As an only somewhat skilled gamer, I can't say with confidence that I won't grow to adapt around Mario and Ivy and begin to like those matches more. It's hard for me to predict whether or not my criticism is sound.
Also, since you guys mostly get complaints, I want to add that I love PM, and I want you guys (the PMBR) to know that. I'm insanely grateful, and this will always be my favorite multiplayer game, and this game is what made me see the beauty in competitive gaming.