A wonderful addition to the Series that brings a number of interesting changes to the formula while still being HALO
The previous games all had one constant rock to steady themselves against, Master Chief and his amazing resilliency. He could sprint, dual wield, take serious amounts of damage, and jump higher than any human. He was basically Superman in green amour. So to have to play as an ODST (Orbital Drop Shock Trooper) felt at first like a major game breaker to me. Before I played it that is.
The fact is that the series had been pretty over the top for a while and ODST seriously brings it back down to the realms of humanity. Don't get me wrong, I love the gameplay from Halo 1-3 and seriously miss the power of the Chief, its just nice to be reminded how much more powerful he is sometimes. Your trooper has less health, can't sprint, can't jump stupidly high and is just generally anything but super. Without wanting to harp on about the same thing over and over I will simply say that despite the fact that you innitially feel under powered when compared to the Master chief, you find your pace and approach eventually match your characters skills.
In previous Halo games I would simply dive into the thick of a battle, guns blazing, plasma flying, melee-ing grunts and generally decimating all in my reach, now with the ODST's you have to seriously consider your health and your adversary. Finding alternative, stealthy detours and shortcuts often provides you with the only edge over an enormous Covenant Brute and his companions.
The story is very well thought out and told in a unique way for the series, I often found the story became hard to follow in the previous games because Cortana was relaying most of it while I was killing Covenant scum!! So its nice to see a well rounded story centering on a group of all together more human characters (voiced by 3 of my favourite Firefly actors!)
I will say that the game is not perfect. The game is still very much a Halo game and so if you don't enjoy that type of game you won't find much else here to like. The graphics engine has been touched up a little since Halo 3 but its still nowhere near other highend 360 games such as Gears of War 2. And the story mode could have been much longer and had more content, and it ended quite abruptly too, I felt a larger, grander conclusion would've been better.
Regardless of those minor flaws, if you seriously enjoy FPS games and the Halo story as a whole then you should fall in love with ODST as it offers interesting new game play, story and atmosphere while keeping true to the series formula.