I just got back from it. My opinion is that it's a good movie. Yes it's not really "Robin Hood'-y but at the same point, it's an origin story and a rather believable one. It makes more sense that this guy would be some legendary outlaw since he lead this army to stop a french invasion and John got his knickers in a twist when everyone loved Robin and not him and decided to throw him to the wolves. The people love him, the king hates him. Good origin and re-imagining for the beginning of things. And it also really sets the stage of John being this petty and greedy tyrant, which he is.
The only big plot hole, in my opinion, is that King Henry is dead so the whole Henry coming back to reclaim the crown from the tyrannical Prince John (In a later movie, obviously) resolution can no longer happen. All the "unconnected" plot points that Bob complains about are, in fact, explained. You just need to *gasp* pay attention.
If you go into this movie in your green tights and expect a straight telling of the "Robin Hood" story as Walt Disney did it, minus the furries, yeah you're going to be disappointed. If you can look beyond that, then you'll enjoy the movie.