Having finally finished the second season- because I'm slow like that- yesterday, it was solid, but definitely a step back quality-wise from the first season, so I can understand those who didn't like this as much as Season One. While the stuff with Jessica's mom is definitely more personable and more investing for her character, it's not as gripping as the Kilgrave stuff was. Consequently, I think the episode where he appears was, for my money, the best of the season. And it makes me wish that Kilgrave had, maybe not a constant, but almost recurring status.
Wouldn't even have to be physical, but maybe just a voice in Jessica's head if they can't get David Tennant. I wouldn't call the season slow since the show, by its nature, is a detective show and Jessica does get to do some actual detective work, but there are scenes I think that drag on longer than necessary. Not often, but some time could be trimmed.
Trish should forget having powers. The fact that she could one-shot Jessica's mom from a distance on a moving ferris wheel shows that her future should be in marksmanship because that's one hell of a lucky shot. And I'm curious if Hogarth/Trinity's condition worsens or improves in the third season. Also I wonder who will return. The super and his sun or the one cop who trusts Jessica, those guys could easily be recurring characters, especially the cop given that someone on the force is actually on Jessica's side.