ODST was the victim of bad marketing. They got way too excited and made some statements that they later reversed and the gaming community isn't very kind about that type of stuff, so it got far more hate than it should have. It is a far more character driven Halo story where you play as an average soldier, which means you are much weaker, and as such you have to play the game differently. I think people had trouble with that concept and wanted to keep playing it like it was Halo 3 and they were Master Chief. You do that and you will die, a lot, and in ways that look rather painful.