I thought Ewan McGregor did pretty good in the movie. I was surprised by Scarlet's mediocre acting, though. Had expected a bit better. For the rest, I loved it. I'm a sucker for visuals, and this movie has it. Great colors, great atmosphere, great design. Also the theme appeals to me, even though I hate "Brave New World" (we had to listen to a god-awful audiobook of it in English class for weeeeeks).
One complaint: The trailer showed waaay too much...