I'd say it's most definetly worth it! I loved that game!
My friend got it and did'nt like the setup of the game, but I loved how you get to follow each squad member and their own "story" what happened after the orbital drop.
I'm currently trying to set up a team for my second playthrough on Heroic, possibly Legendary, but very few (none) at my local 360-site is willing try it cuz they seem to think ODST sux
I read a few books as well and think different events outside of the Master Chief main story only makes the Halo universe a richer one!