Well, I think he's been called dumb, so he might be a slow learner. There were mentions of character concerns before he was drafted, but the only thing I could find is that he made a business decision to skip Georgia's bowl game before he was drafted.
Then, there's this robbery. If nothing else, he put himself in a bad situation. But just because the charges were dropped doesn't mean that he didn't do it. There seems to be evidence that he and Dunbar tried to pay off their accusers (and that the accusers tried to get more). He could have done that because he just wanted it to go away or because he's guilty.
I also read he was considered to be a good teammate, but then I just read this:
“There was a battle in our building on whether we were going to take DeAndre or not,” a source privy to the Giants’ draft thinking told The Post, “because the story was he had to have his a– kicked every day to work hard at Georgia — to even go to practice. We knew that and we still drafted him, and from Day 1 it was like taking a guy in the first round that you had to teach nearly everything to.”