@pongley: The Batmobile is surprisingly quick, I would say that it's definitely easier (and quicker) in some scenarios to hop in the Batmobile.
Personally, I love gliding around, but I found it exciting to jump in the Batmobile when going to a mission or moving between objectives, it lets you maintain that sense of urgency.
Flying about definitely feels like something I'd default to when just exploring the city. Or when I just want to harass goons on the road.
I think we're getting best of both worlds here, I like being given the choice. Plus that thing is an absolute beast, proper power trip driving it for the little while I did.