That tendency to hold onto the ball arises mainly when he is carrying it forward. When he broadly holds his position and looks for a pass based on the movement of his team mates, he doesn't seem to me to be more guilty of hoarding the ball than anyone else. And all of that is, I think, because he is looking for a "safe" pass, by which I don't necessarily mean one that is unadventurous, more that it is a high likelihood of completion (hence his high pass completion stats). In short, he is a player that likes the team to keep possession.
As far as his overall role is concerned, I see him as a quality squad player. I don't ever see him becoming a first choice player, but I'm also not foaming at the mouth every time he starts. He may not set the world alight but he rarely has a stinker and lets us down. Kind of a midfield version of Steve Finnan, which is no bad thing.