The games got better with each generation. I've played Red/Blue/Yellow, in retrospect, they were terribly designed with some bland Pokemon names and designs. Understandable, Gamefreak did not expect the games to do well and were experimenting with what to do.
Generation 2 was better, definitely an improvement.
Generation 3 was amazing, introducing abilities, natures, the current IV/EV system and some interesting Pokemon. They really started shaping up.
Generation 4 improved even more, adding the special/physical split and even more unique and interesting Pokemon.
Generation 5 is easily the best so far. Added tons of excellently designed and cleverly named Pokemon, implemented a myriad of new toys to play with in the metagame, and even dares to question the very premise of the entire series. Not to mention putting in some actual character development.
All in all, the Pokemon games get better over time, and hopefully continue the trend in the 6th generation.
Hurray for Pokemon.