Have to disagree with that "still fun for casuals" part, to some extent. Not that it's terrible for that purpose, but it's not as good as vanilla Brawl. The stage list in Project M is a repetitive snoozefest for casual play (even going as far as making some really fun Brawl stages, like WarioWare, super boring), and for some strange reason, they don't let you pick up items while dashing, which feels really counter-intuitive for casuals (and keeping the feature would not have effected competitive play - it's literally only removed to make that aspect of the game more like Melee, for the sake of it, rather than being of benefit to anyone).
And while Turbo Mode is awesome, it comes across as more of a "fun for advanced players who want something crazier" kind of thing, rather than being fun for casuals, since you need to be very good at the game to really see the effect of Turbo Mode.
And in it's current state, PM removes some rather fun single-player modes like SSE, that also have co-op play.