Lebron is the best at what he does, which is using his athleticism to beat his man off the dribble and penetrating. He might even be better at that than Jordan, given his size and strength.
The problem with Lebron, though, is that he is a worse all around player than Jordan and, currently, even Bird. His 45% eFG% on jump shots is terrible (compare it to Pierce's 51.5%), he shoots less than 40% on the long 2, and his 35% 3fg is not good for someone who attempts 5 3s a game.
Now, those numbers are relatively reasonable when compared to other good players of today, but when the talk is "best of all time" or "top 5 of all time," those numbers point to significant limitations in his game.
So until he gets a jumpshot or a post game, I wouldn't compare him to Bird or Magic, much less to Jordan. His multiple playoff failures show that. He can get there, but its not a given.