I think his compulsions tend to be things like wanting to live up to everybody's expectations, wanting to help everybody, sometimes spreading himself out too thin or maybe being too trusting on occasion as a result. So, that kind of means his flaw is that he's *too good*, which can be annoying to others and/or detrimental to himself.
At a lot of points in his life, he's not only been Batman's partner and go-to guy, he's also had his own team or city on the go: Teen Titans, Titans, Outsiders, protecting Blüdhaven, being a cop in Blüdhaven, and now out of loyalty and responsibility he's stepped up to become Batman and take hell-child Damien under his wing as Robin, but you just know the Justice League will come calling one of these days too.
He's not as tightly in control of himself as Bruce was/is, and probably needs a bit more time/space for things to be fun in order to stay sane, so I can see him wearing out more quickly than Bruce would.
If he's in a good place in his life, he's comfortable with himself and who he is. But if he's not, he can kind of be bogged down by the fact that in some ways he's like-Batman-but-not-as-good, despite having other skills/qualities that Bruce doesn't. Bat-shadows are always troublesome.