What can I say, I love this kind of movie. Where a group of losers form a solid friendship and success in whatever they want to accomplish, after a few struggles and when no one would have given them a chance.
I have to say that Hiro impressed me with his English accent. It was good and not awkward at all. His hair was a bit MEH; straight hair does not suit him and sometimes, he looked a bit like Michael Jackson. But he played his role very well; I thought sometimes he actually played the guitar (I don't know if he did or not).
Sato Takeru was OK I guess, in his role of Koyuki. The typical nice, naive boy from school, that is bullied (by no other than one of the "Crows" members!) and has basically, no interest in life. Until he meets this rocker and wants to learn to play guitar. I was more impressed with the bags under his eyes, to be honest. Such a young boy with that issue. He should have gained more weight (he was too thin when he was younger).
Osamu Mukai does well whatever he plays. Although I may prefer him in this kind of role, more tough. I did not like his bleached hair at first, but after a few minutes, I was OK with it. He did very well his role as a bassist; not too many lines but his presence was enough for me. Second best in the cast.
Kiritani Kenta was the best actor for me in this movie, hands down. I liked his rap, his crazy hairdo, and that scene where he fights against the bullies. He has such a funny face.
At least the female role in the movie, in the hands of Kutsuna Shiori, made sense (unlike in Crows :P). Her English was good, and I can't say anything bad about her acting. The transition from English to Japanese and vice-versa was well accomplished, and I liked when she was frustrated and yelled in English.
I also liked Sakurai-kun, new student at school and Koyuki's new friend. He had a good chemistry with the band, and looked to kind.
There is a good soundtrack, my favorite the one at the end ("Don't look back in anger"). There are some negative reviews about Koyuki not actually singing in the entire movie, but it did make sense to me, and I like that we only need to see people's expression to know he has a marvelous voice. Since the movie is based on a manga, and it is very hard to please people regarding something delicate as A VOICE, it was good they made it this way.
My only complain would be the length of the movie (2 hours and a half). It never drags nor it is never boring, but it is long.