I just started Idolmaster too! I don't expect to blow through it either as I've yet to watch a proper Idol series, but I was really surprised at how great this series is visually (so far).

There's actually a lot of Trigger and old Gainax staff sprinkled throughout the series (not just the ep Trigger animated), probably because it's mostly Nishigori's series, who's worked on a lot of popular Gainax and Trigger series. It almost seems like a collaboration of a ton of different talent, with titans like Tsurumaki or Imaishi storyboarding whole episodes themselves. It's funny, art is not what one would expect from a show titled 'Idolm@ster'.

here's the ANN page if anyone's interested