My opinion. There are a few Pokemon from Gen 4 I like, but they are outweighed by what is, in my opinion, a very unimpressive selection.
Now this is just about Pokemon designs, not the games themselves. Platinum is still one of my favorite games in the series. I expect a lot of people to disagree with me, but I'm curious what you think.
D. For the most part, there's an equal amount of 'mons that I like and dislike each gen. Except maybe 1, since that gen are a lot of designs that I find boring, moreso than other gens, like Sandshrew, Pidgey, Ditto, or Exeggcute.
Gen 4 was kind of hit and miss; there are some fantastic ones, and a lot of unremarkable ones too. I personally like Gen 3 the least, but that's more because they have a distinctively different style to everything previous that mostly just wasn't to my taste.
C I guess. Gen 4 was definitely the most under-whelming, even if it did spawn a handful of my favourites.
[LoL favourites: Janna, Syndra, Rumble, Fizz, Ezreal, Miss Fortune, Katarina, Volibear, Ahri, Lee Sin, Kog'Maw, Sejuani, Wukong, Nunu, Swain]
I actually did not like Gen 4 for some reason. The pokemon weren't bad. They just never really grabbed me personally. I did like Giratina, Darkrai, Luxray line, fossils, starters, and the new evolutions.
Actually I liked a lot of the pokemon form Gen4 the game just didn't grab me for some reason I guess.