Getting right to it, David Goyer's Batman Begins script gets a big thumbs up, the J.J. Abrams' Superman script doesn't really. Both of the films will be changing the origins of the character, but the Batman origin will be more in line with what was written in the comics before. It is very conscience of staying true to the Batman character.
With Superman, it apparently gets too formulaic trying to connect things. For example, the Smallville story keeps you intriqued, but the new Supes film's story does not. With Batman you want to go deeper into his journey to see what's next.
Our source says that Goyer makes it feel like a Batman movie at all times through locations, etc. Even scenes where Batman is not present, it still feels like a Batman film. It also has a lot of "Batman: Year One" in it (in a positive way), which probably explains why the studio didn't go for a separate "Year One" film.
'Enigma' adds that all the characters are excellent in Batman Begins. There's 3 villains (Ra's Al Ghul, Scarecrow, mob boss Falcone) in the movie, but it never feels cluttered. We're told that the Batmobile scene is simply amazing and that it's hard to believe they won't be using CGI for it, considering what all the vehicle does.
The source also says that Batman appears in the movie about as much time as the Hulk did in last summer's adaptation, though the time he'll be on-screen will be "awesome".
Some favorite scenes and more details? Turn back now if you're trying to avoid big spoilers!...
The Batman vs. Scarecrow confrontation is supposed to be spectacular. And the best scene in Superman, where he rescues Lois Lane from a plane crash, will probably be stunning.
Also Ra's Al Ghul, played by Ken Watanabe, doesn't speak a word of English in the script. He instead has a translator who does that for him. And the Batmobile in the film will be referred to as the "Tumbler," it is designed by Wayne Enterprises for the military.