I just started this game. So far, Lissa's hanging pretty close to my Avatar, who regularly needs healing (low HP; yeah I know that makes things harder, but that's intentional). Though I'm not necessarily going to pair her with him… we'll see.
This is a nice drawing of her, although she looks somewhat more serious than in the game.
Yeah I'm pretty excited to see some of my favorite characters again, though I hope they will fit into the story naturally somehow. I would love for this game to add something new to these characters rather than them just being units that you can use, in which case, I can't help but wonder why wouldn't I just go play their respective games if I wanted to use these units? But for nostalgia reasons, I will definitely be getting them, and I hope Ira will be as awesome as she was in FE4!
I never thought about emulation as an issue because after all, it's free! But you bring up a good point. I think the DLC/ SpotPass characters will be more appealing to people who have played the previous games though, but the changes to the battle system will be fun to try on old characters!