I thought Radiant Dawn was a good game, but I preferred Path of Radiance. PoR was the first Fire Emblem game I played and I think it somewhat spoiled me. It feels more polished than any of the other Fire Emblem games, and most importantly the difficulty curve feels just right. In Radiant Dawn I remember a few of the early battles being on the hard side compared to the rest of the game.
Still I had a lot of fun with Radiant Dawn too. I think part of it is that I wanted to play with Ike and the rest again.