Without a suit, Nemo is practically defenseless. You can jump over them, but Nemo can't jump very high and many of the monsters are rather big. I don't like having to dodge every creature on the screen until I can get a suit. Once you reach Nightmare Land, you are given a magical scepter than can be charged up and used to attack, but this only fires in a diagnol upward direction. Another quibble is the level structure.
Some levels are downright annoying too.
The third level involves simply riding on a train, dodging airplanes and ducking under spikes. This is also one of those levels that you don't get any animal suits, making things very, very annoying. The graphics are more than just passable. Although nothing extraordinary, they are pleasant and well detailed. The music, for the most part, is rather annoying with the exception of a few tunes here or there.