The first episode had so many awkward moments/dialogue that it ruined the entire episode for me. Many voices didn't fit, but in most cases, the actors who played them were alright. Kamina bothered me, but as someone mentioned, he got better in the second episode. I was taken aback by Yoko's voice at first, but I gradually got used to it. Leeron's voice was fantastic, and I wasn't bothered by HARD MANLY TWIST, as someone brought up - In fact - I was pretty amused by it. It fit.
The things that did not get better for me was "Team Gurren" and "Seemoan." It's still weird for me to hear that.