Dawn of the Dragon is a little bit diferent from the previous 2 due to the change of the developer (Krome didn't like the end result of The Eternal Night and suggested Etranges Libelules to develop the next game because of their high quality products with small budgets).
The graphics are a lot different (less cartoonish) The combat is more complex with a lot of combos More exploration but is flawed due to invisible walls. Co-op, which is kinda cool.
PS2 and PS3 versions has the exact same game. The diference is the high quality textures on PS3.
Spyro the Dragon was actually the first game I got and one of the first games I ever played. I was a huge fan of the original trilogy and Spyro was my favourite game series until Ratchet & Clank. I recently got the games from PSN to play them again actually. I still have the disc copies of those somewhere, I just don't know where they are.
About the new games… I haven't played Spyro games that came after "Enter the Dragonfly", but I would probably give them a try if I ever have a chance. I'm open-minded even for Skylanders, even though they're not exactly Spyro games but anyway.
Now that we are talking about The Legend of Spyro trilogy. Forget the flawed gameplay, what did you think about the redesign of spyro, the mithology and the new universe of Spyro? I enjoyed it a lot and I think it was a step foward to the series.
Redesigns are alright for the most part, even though I have to agree with Darkstar that Sparx is, well, quite odd. The story and world of The Legend of Spyro seems like every teenage fantasy book. Not that I know much about it or there's something wrong with that.