HORRIBLE!!!!!!!!!!
I'm just going to start out by saying that this game SUCKED!!!! So go grab a bowl of popcorn and enjoy the presentation of how awful Halo ODST is.
First off, the campiagn. It starts out interesting, putting you into the shoes of an ODST soldier named Rookie. The story doesn't give you much information about the faceless soldier, leaving you feeling like your just a shadow walking around with a gun. The story basically starts out with the ODST drop going awry, sending all of the pods sprawling out across the city. Rookie's pod ends up getting caught on a pole or something and is suspended twenty feet above the ground. He jumps out, and soon your exploring the dark and eerie city of New Mombasa. The weapons you start out with are fairly simple, machine gun and pistol, but it doens't need to be very exotic at first. The character needs to get the feel of the game. The music is nice, adding to the feeling of loneliness and dread as you walk around the city. Mind you, in that situation, loneliness and dread only add to the experience. If you were walking along a sunny beach and that music was playing that would be one thing. After a couple minutes of exploring, you run into some alien Covenant, and soon your blasting away aliens like the Halo you know. The combat is pretty good, actually, varying night vision use and normal sights in a nice way. The game starts out good, combining action and exploration. Mind you, the campaign is good, but compared to Halo Reach is horrible. You also have the secondary option of finding pointless collectibles called Autologs, which basically tell a side story of their own. These are stupid and boring, making just listening to them a drag. Along the way of the campaign you play as different ODSTs, such as Buck and Mickey, and some of these missions are fun, but not fantastic. In some missions you'll pilot Scorpion tanks and Warthog gun trucks, and in one a Covenant Banshee. The ending is ok, leaving a lot of questions unanswered. Where the game goes bad is after you beat the campaign. If you don't have online, you mind as well just break the disk and throw it out the window after the story is done. What you're left with is Firefight mode. Compared to Halo Reach's version of it, it's Pacman on the Atari. It SUCKS. There is hardly no customization to it, and the only thing you can change is the difficulty and area you're on. You can't choose what weapons you start with, what aliens you face, or anything like Halo Reach. Also, there aren't any unlimited ammo crates, so at some point you'll end up running out of your typical machine gun ammo, and probably most other weapons except Covenant ones. This is extremely frustrating if you've played Reach before. Also, there isn't Forge or split screen competitive multiplayer. This really takes away from the experience.
If you don't have online multiplayer, don't buy this game. It's a waste of your time and money. Also, if you want to play this game, play it before you play Reach. If you don't, you'll hate ODST. In fact, you'll hate ODST anyway.