Graphics/Soundtrack

Like all Halo games, Halo ODST is beautifully constructed.  Since Halo 3 is both recent and graphically pleasing, ODST doesn't offer any huge leaps in that area.  The dark city environment of New Mombasa can be eerily exciting, and lends itself well to the dark storyline.  The excellent score helps make the action-packed parts of the game that much more intense.

Appropriateness

Halo ODST is a first person shooter in which humans in spacesuit armor attack alien invaders with rifles, machine guns, laser weapons, and grenades.  It's rated Mature by the ESRB for Blood, Language and Violence.  Violence in a first person shooter shouldn't come as a surprise to anyone.  Players see the end of their guns, aim and fire upon enemies.  The good news is these enemies happen to be blue, green and grey aliens, not human beings.  While this may not put every mind at ease, it will certainly ease some that the violence depicted in Halo ODST (while rooted in gun combat) is highly fantastical.  As far as the use of Blood in this game is concerned, it's generally for scenery.  The alien blood is not red, which makes it appear more as a jelly than actual blood.  Dead soldiers laying here and there are fairly lifelike though, and may be soiled with red blood.  The use of vulgarity by the characters is tossed in here and there throughout the storyline, but isn't gratuitous.

This games Mature rating seems unfitting for the highly fantastical violence and blood during gameplay.  The language is also barely comparable to a PG-13 movie.

Conclusion

For Halo fans, Halo ODST is both welcomed and disappointing.  If you're expecting a new storyline packed with detailed event descriptions and solid campaign gameplay, you won't be disappointed.  If you're looking for a more robust multiplayer experience with new weapons and a plethora of new maps, you'll be highly disappointed.

If you've never played a Halo game before, or you dabbled here and there but haven't kept up with the storyline, the campaign will likely be somewhat confusing for you.  In fact, you'll be all but in the dark unless you do a little online reading of the past plotlines.
If you enjoy first person shooters like Gears of War, Call of Duty, and Resistance you'll likely find the gameplay of Halo games to be somewhat slower than you're used to.  Some prefer the speed while others do not.  Either way, Halo ODST deserves a try.

(Rated M for Mature | 17+ age | Blood, Language, Violence)