Got Project M a few days ago. I have to say. That it is AWESOME! I was worried it was going to be a straight up Melee clone (since it is officially called Project Melee), however I was wrong. Yeah it was meant to play like Melee, but they did take elements from all three. From Super Smash Bros. on the N64, Super Smash Bros. Melee, and Super Smash Bros. Brawl.
Some characters got barely any changes, like King Dedede and Snake. While others got some changes to them, like Mario and Link. While others got an overhaul, like Wario and the Pokemon Trainer, whose Pokemon was split into three separate characters and certainly for the better.