I understand that
1) this is an old, tired argument
2) we're not dealing with Christopher Nolan
but I would have hoped that given some past casting hooplas people would have learned to be a little more patient and trusting with these things, especially two years out from the release date when we don't really have any idea what the intentions are with these characters. For my part, I was sorely disappointed with Man of Steel walking out of the theater, but I've since watched pieces of it on YouTube dozens of times and have found a lot to like about it. If nothing else, it leaves a tremendous amount of viable material to be explored in a sequel. I was never, however, unhappy with the casting. In fact, I still think it was excellent, even if in a film that I felt had a somewhat poor sorting of its priorities where screentime was concerned.
Are we going to get a one-to-one adaptation of the classic DC Comics Aquaman? Eh, probably not. He's not likely to be blonde, for one, which is in my opinion a really stupid quibble that's going to get far too much attention. But I don't know how badly many people actually want classic Aquaman. I understand in the new continuity he's had a pretty well-received run, but it's his more serious incarnations outside of comics (DCAU's Justice League and Justice League: Unlimited, the alternate universes like The Flashpoint Paradox and Injustice: Gods Among Us), to my understanding, that have seen him more well-received. If Snyder and co. are looking for someone to embody the ferocity of a foreign king, it's hard to top Momoa's glowering gaze, exotic looks, and physical presence. I can sympathize with reservations about his acting, but I think it'll work out. And if it does, he'll do great things for the character's visibility down the line.
And since I've already brought up one of the best screen adaptations there is (DCAU), I just want to say that the classic DC Universe at large does not lend itself particularly well to live-screen adaptation in a modern setting. Sorry, but it just doesn't. Some character fare better than others (see: Batman) and there are fantastical standalone arcs that I think could be incredible on the big-screen with the right people (All-Star Superman) - if not commercially viable - but building a cohesive, believable world with characters that exist and interact authentically has always been Marvel's forté. If the creators of the cinematic universe feel they have to depart from the template here and there to adapt it to film without losing the essence of the material, then so be it. And if you're in the camp that thinks if it's going to be different it's going to be worse... the resources do not exist to make the movie you want to see.