Possibly the most hated generation of all time, Generation IV is the subject of a lot of controversy. It also brought back many fans which did not play a Pokémon game since Generation II, as many skipped the third generation.
One simply must look at my flair to see my opinion. I believe that it is the absolute best generation, with my absolute favorite game in the series, and my favorite game of all time, being Pokémon Platinum. I believe that the game has a spectacular region with a distinct mature feel, which is reflected within everything, and the new Pokémon introduced were simply amazing. They were the opposite of Mega Evolutions; they were dedicated to breathing life into Pokémon which many previously forgot (except Eevee).
Anyhow, give your opinions within the comments.
