Bisping has to actually sit on his punches to have a shot at winning this fight, Sonnen has a good chin and will just walk through his punches if he decides to try to outpoint Sonnen in a standup match.
I like the fact that Bisping seems to be in the mindset to not be afraid of getting taken down, and actually expects it to happen at some point in the fight. Sonnen is good at keeping top control, but he doesn't really do vicious damage while he is on top, and seems to be content with just controlling his opponent and winning the round. Also, I don't think Bisping is scared of Sonnen's power, this makes me believe that Bisping will go for broke in the standup game and aim for a knockout.
I see Sonnen getting the decision, but I also expect Bisping to hurt him standing up a couple of times.