I loved the original MDK, and still have vivid memories from playing it to death way back in 1997. It was a smart, funny, beautiful, technically impressive, engaging game. Shiny deserved every kudos for it.
I eventually got MDK2, and really really wished I had not. It was not made by Shiny, the original developers, but by Bioware, and is almost certainly their worst title. I played the entire game and tried to like it, but it's so mediocre (sometimes awful), especially compared to the first, that I regret the purchase to this day.
If you're looking for something in a similar vein to the original, I can't say there's anything else that does what MDK did so well, but Sacrifice (also by Shiny) and Giants: Citizen Kabuto (by Planet Moon, founded by former ex-Shiny crew) have similar aesthetics and are well worth playing.
Maybe MDK2 is somebody's favorite game, but I just want everybody expecting a good sequel to have fair warning.