Though I've seen many a home-made Master Chief from HALO costume, THIS is the first I've seen that is an officially licensed costume.
Pros: Looks pretty good for a store-bought costume. With some tweaks and the right weapon you'll definitely get some props.
Cons: Hope you have deep pockets because this baby will set you back $630.
Also: The only size available is a Male chest size of 42-44. So if you're a slim guy, time to start doing push-ups. Lots and lots of push-ups.