Hyped up to halo, no, sorry.
Graphics: Halo ODST is better, but these aren't bad.
Gameplay: like any-other FPS, short campaign and annoying online.
Online: Rated T, so get ready to turn off your volume off, just like anyone other FPS just run around shooting people with and do the respective objects before a certain time.
AI enemies: Pretty much all the same, semi-smart AI, will try to move around your cover and will take cover themselves.
Maps: Meh not to bad, since you have a jetpack, no map is really better than another.
Bottom line: For my 7.5 rating here are pros and cons:
Pros: objectives are good for teamwork--cheats give you 2 cool guns and new armor--its cool to fall from the sky as a comet--partial destruction of area
Cons: TERRIBLE vehicles, sniping is a mess, no places to snipe(jetpack), less than a halo rip, online giggling and farting 10 year olds, nothing that really stands out form other OK FPS.
that's about it. hope this helps!