When it comes to platformers on the Turbo I'm much more of a fan of the likes of New Adventure Island, Jackie Chan's Action Kung Fu, Ninja Spirit, Dragon's Curse and Legendary Axe 2, to me Bonk is more on an A- tier (I'd say B tier if we were to compare it with platformers on the Nintendo systems), but once I got the hang of the controls, and it took a while to get the hang of them, but still, when I did I started to appreciate the games a lot more...
Esteban describes it well enough in his post, but if I may add my own two cents, Bonk is a game that the more you play, the more you're acquainted with how it works and feels, the more you'll probably like it, I mean, when I first played Bonk I thought it was just okay-ish at best, but I'm at a point right now where if I start playing either Bonk's Adventure or Bonk's revenge, I'll only stop either when I beat the game or get a game over, I just don't want to stop playing for as long as I don't run out of lives!
Oh yeah, that's another thing that Bonk does that I love, is how it handles lives, like, when you die you don't go back to the beginning of the stage, (or god forbid, the beginning of the game) you don't have to re-do anything, you just lie there for a couple of seconds and then re-start from where you stopped!
Also, my dad doesn't have a lot of knowledge or interest in games, but he has watched me playing games on lots of systems a few times, Super Nintendo, Mega Drive, Playstation, Wii, NES, but when he saw me playing Bonk's Adventure, that was the first time ever where he actually praised the game's graphics... I don't know if that means anything, but I thought it was worth noting...