A good game littered with small things...
...which steal away from the fun and playability factor of the game. This was a great concept but unfortunately there were many things that took away from the overall fun and playability.
The enemies had a few problems. First, their random spawning got annoying and at times ridiculous. When they died and you could eat their bodies, often times the bodies would be too close together and you would not get to choose which enemy ability to take, it would simply eat a whole pile of bodies and give you one. This was especially annoying when you were trying to get a certain ability.
Speaking of abilities, some of them were bogus. For example, there were situations in which you needed the flying ability, but that didn't include the flying attack that the flying enemies could use. You were stuck with the underpowered normal punch attack, which you couldn't even use in midair. This resulted in a lot of unnecessary damage, especially if random enemies kept spawning and dying in a pile so you couldn't get a better ability. Also, the best ability in the game was by far the overpowered yellow blob's ability, which surprisingly was nothing like that actual enemies attack.
Also, the actual map layout wasn't as much of a problem as the viewing perspective. Compared to many other games, the main character was very large in proportion to what else you could see on screen. The platforms and ground were very thick and therefore also took up a lot of screen space. You didn't have a very good viewing angle of what was going on, especially when jumping on the huge mushrooms which also took up a lot of screen, and bounced you just high enough so you could not see what was below you as you tried to jump.
The killing enemies to continue onward is a very popular arcade style technique, which is a great effect in side scrollers like Metal Slug or the TMNT arcade game. However, this game is not a traditional side scroller like those games. In this you need to go up and down, sometimes to the left, and you are free to backtrack unlike classic sidescrollers. So when you reach a dead end, you're not sure if you have to fight enemies, or maybe you taken a wrong turn, or maybe there is another path somewhere.
A couple more small things, the life display is WAY too small and tucked in the corner. It's hard to read, and when you look at your life it pulls your eyes far away from the action going on around your character. There is also no indication that your life is getting low at all. The music is nice and fitting, however the loop is very short so it gets repetitive very quickly.
Overall its a good concept that is a nice original adaptation of another game, not just a bsic rip off. There are a lot of nice things about the game, but also much room for improvements and more ideas. I could see this game becoming much better with some more work put into it.