I didn't like the cartoonish look of Samus in MP2 and 3 either, but the games themselves are almost as good the first one. I think the first game had the best level design of them all. It seemed like a continuous world even though it was divided into 4 or 5 parts. It's the way they were connected - very organic. MP2 had a central hub area from where you could go everywhere and seemed to be more artificial. MP3 had the world divided into planets and your ship acted as an elevator.
If I had to rate the games it would look like this:
MP1 > MP3 > MP2
It's also the only FPS I will play voluntarily with a controller because of its different control sheme
If I had to rate the games it would look like this:
MP1 > MP3 > MP2
It's also the only FPS I will play voluntarily with a controller because of its different control sheme