The game was pretty fun. I was hoping they would try to make the game squad based like Rainbow six (at least on the daytime missions).
Firefight is tons of fun.
Finding all 30 audio files got rough towards the end. Just remember Virgil(the AI) will try to get your attention with detour signs and street lights when you are close to one. As for the last file highlight if you want its location:
You must have all 29 files found in the city. After you enter the underground you will come across a Cop on his way down to sub-level 9. You will both come across a frozen door. The cop will open it and ask you to wait outside. Ignore him and be prepared to shoot him in the face. After he is dead pick up te last file which is the phone on the wall near a body.
If you haven't paid for any of the halo 3 maps the multiplayer disc for ODST has them all so save your MS points.
Overall its a fun game if a bit short (depending on the difficulty you choose), but if you're like me and like to do the occasional achievements you'll hardly notice.
Edit: Forgot my tag StereoEsen Hit me up for firefight or Co-op Goodness