I actually really like(d) Gen.4 :) I don't know what it is exactly, but somehow the game still appeals to me a lot each time I play (or want to play) it.
However, there are still some Pokemon in Gen.4 that I don't like or are not necessary in my opinion, mostly the "additional evolution Pokemon", 9/10 they spoiled my feelings and ideas to their previous evolutions and are just overdone:
1. Probopass - Definitely one of the Pokemon I really dislike (at all times) because of how it looks (mustache - why?!)
2. Magnezone - Yeah, just looks weird, I don't like the ufo-look and I think the Magnemite line was done with just Magneton, nothing more
3. Lickylicky - Seriously, looks so weird imo, it should just have been Lickitung alone, no evolution
4. Tangrowth - Again, kinda same story as Lickylicky, why did Tangela need an evolution?
5. Rhyperior - I'm a huge fan of Rhyhorn/Rhydon but Rhyperior spoiled everything (no offense), it's just... overdone imo