I absolutely hated the movie.
While I loved the casting, the characters were under-written, and as you said, under-developed.
If you're gonna cast Bale and Depp, dont slap us in the face with crappy writing.
The movie was beautiful, and aesthetically pleasing throughout, and i enjoyed the soundtrack, but the audio was very poor.
The studio even sent out a letter to theaters requesting they raise the volume a whole 30% (which by theatre standards is extreme).
Also - I thought there were WAYYYYY too many characters in this movie. I guess they decided to go the buffet route: quantity over quality.
SPOILER (kind of)
Everyone knows the story, Dillinger dies...but when it happens in this movie, you dont care. it's not bothersome when the main character
of the movie dies, simply because you do not develop an attachment to him over the course of the movie.
That's a problem.
I've never been a Michael Mann fan, and my dislike is even stronger now