One of the bad things is in Platinum, you never get to battle Charon. I wanted to battle him, but Nintendo decided to not make him battleable. That was a disappointment for me. And the slow surfing speeds in Diamond and Pearl were atrocious. In HG/SS (This is before I played Crystal, but after I played both Blue and Firered) I was quite disappointed because Pokemon Tower in Lavender Town was a lot smaller than in Firered and Blue. But that was it.