I'd say you have McNutt and then...no one. Maples hasn't even registered any actual minor league innings yet, and coming into the draft he was considered to have one of the best curveballs in the draft. I don't think any legitimate opinions can be made until he pitches at least a year. I've only seen video of him pitching, and his delivery is...awful. I see him as a future RP.
I'm really surprised the Cubs did not decide to spend this past winter and the 2012 season reworking his delivery. I'm not sure why they are content to let him pitch with it, but that's the story I'm hearing.
I don't think it is a good idea to rework someone's delivery until we have seen whether it works for them or not. Altering a delivery can most certainly have negative side effects (less movement, location issues, etc.) Let's see what the kid has and suggest minor tweaks at first. If there is glaring issue that needs addressed after we have seen him for an extended amount of time, then I think we could have that discussion.