Well, Radiant Dawn is split between three different "arcs". Kind of like Awakening except they are actually split off from each other with different characters and parties that meet up later. It has pretty much the same Laguz gameplay from Path of Radiance, and a lot of returning characters. I don't know how much is different mechanically from Path of Radiance since I didn't get very far, but it seems relatively the same. I thought it was pretty difficult in the Easy Mode, (Normal Mode in Japan, it was mistranslated), though that may just be because it was my first game, and first SRPG in fact. I later replayed it once on Normal, but it was awhile ago so I can't remember how hard it was.
I liked the story when I first played it. Now I like it about as much as Awakening's, more than Blazing Blade and Fates, but less than Sacred Stones and Echoes. I also really enjoyed the characters, with some of my favorites besides Naesala being Haar, Shinon, Volug, Lucia, Leanne, Sothe, and like most people, Ike.
The Final Chapter was really memorable for me. I'm not going to spoil it, but it definitely made a good impression.
I don't know how good this description was but hopefully that gives you some idea. I recommend it for sure, but it's really hard to get a hold of these days