Aesthetically and stylistically unmatched, and while I didn't play this one as a kid, Gen 5 is probably the most nostalgic a game ever felt to me (besides Pokemon X and Y)

That said, its still the 8th copy-paste of Pokemon RBY and probably the easiest Pokemon game at the time it released (assuming you're not doing a nuzlocke). Literally you can get a Lucario extremely early and have him one shot the entirety of the late game like I did.