I bought ODST a few weeks ago, and until earlier this week, it was pretty much gathering dust. Not for the lack of interest, but lack of time and opportunity to play the game. I haven't gone far in the game in the last few days, but so far I'm liking it a lot. There's this sense of claustrophobia and vulnerability that changes the game play from previous Halo games. It's quite refreshing.
Here's a well put together rap video of the storyline for Halo 3 ODST from the guys at JT Machinima.