Gamepro has published a post release interview with Tim Schafer talking about his experiences developing Brütal Legend and some of the design choices as well as what kind of feedback he has been getting while playing online and spreading his viral "Six Degrees of Schafer" achievement.
He also commented on balancing the game and adding more downloadable content (so far one multiplayer map pack has been released)...
"GP: You've introduced a few new maps via DLC. Are you planning to add any single-player content?
Schafer: We definitely want to do more DLC for both single-player and multiplayer, as well as some tuning patches.
GP: What do you think needs to be tuned?
Schafer:Watching people play Brutal Legend makes it seem that certain units might be overpowered, like some players will just spam Fire Barons. It's an interesting issue because you can counter that strategy by using Skull Rakers or double-teaming with a Razor Girl or Bride, so we're testing to see if people are learning to use those counters and once we find the exact tuning tweak to make it perfect we'll implement it in a patch. It's tough to avoid the pendulum effect where you go back and forth, so we try to focus on one fix that will make the game more fun."