I grew up with this game, so I know what I'm talking about. If you don't mind some toilet humor, this is worth a look.
The enemies you can expect to encounter are rather silly and have their own unique personalities embedded into their animations. For example, the the Booger Goblin (much like goombas with an attitude) is on constant patrol, waiting for the protagonist to come near so he can give a quick jab with his spear. When he comes across another Booger Goblin, he gives a hearty salute and goes about his merry way. Another enemy that I enjoyed was the Abominable Sewerman. His shrieks would make my skin crawl every time... The bosses on the other hand can be quite tough, but playing against them enough and memorizing their patterns of attack will yield victory.
Speaking of sounds, the voice samples are not that great, but they're accurate from the days of the Genesis. Aside from the voices, the sound effects and music are both pretty good, conveying the mood of each level quite nicely.
The controls are pretty sharp, though flying takes a bit of practice to get used to (though you won't be doing much of it through the game). The platforming could be somewhat difficult to those that are fairly new (or not very good at) platforming games. The powerup system is well-balanced, though it could get frustrating when you have a full arsenal of upgrades and suddenly lose them with one mishap.
Overall, I would say don't judge a game by its coverart OR its title. Though in the long run it's childish and immature, you can't help but chuckle every once in a while at the antics of this charming game.
Sidenote (if you don't want access to the level select, don't read any further!)
at any point in any level, tap these buttons in this order: up, down, left, right, 2, 1, A (if you're using the wii remote)
This cheat should also give you full powerups, so use at your own discretion