Rev pretty much covered this topic with his last Rev Rant, but here goes anyway.
I have 28/29 audio logs in the streets in ODST and it's driving me crazy! These little logs add nothing to the game except a little side story, but that I'm only missing 1 of them is just irritating. I have no clue where to find the missing one, and since they're not numbered you have no way of knowing which one is missing. I'm looking forward to hours of running around trying to luck upon the Superintendent's flashing lights. Yes, this will bug me until I get it. I'd be fine if I was missing 5 or 10, but missing 1 is just nerve racking.
That said, I found ODST rather interesting and fun to play. Frustrating at times, but really well put together. Mainly I only had trouble playing Legendary in the later levels with a friend. I still have to go through all the pre-Data Hive levels on Legendary though. I haven't yet touched Firefight or the Halo 3 MP maps I didn't previously have. Mainly my friends have just been busy with other stuff.