I'm fine with most the casting choices, and I actually think Fassbender could make a pretty awesome Batman. I just don't know if I see it happening cause I would imagine who ever plays Batman in the JL movies is going to need to sign a 3 picture deal for straight up Batman movies.
Though I agree that Biel doesn't work for WW. She's a great actress but she just doesn't have the look. I don't know who I would cast, but I'd really prefer some one who looks Greek, and was tall.
For me the line up ideally would be Superman, Batman, Wonder Woman, Flash (Barry Allen), Aquaman, and Green Lantern (Hal Jordan). Like it was said let the sequel introduce/add guys like Martian Manhunter, Green Arrow, Hawkman/girl etc. Though I have a feeling they'll want this close to the new JL line up, and we'll see Cyborg added in there.