Good game, cant help feeling like ive done it before
Campaign - interesting feels like typical halo campaign so its your typical aliens attack fight em off halo theme with some interesting cut scenes which are fairly entertaing. though some of the cutscenes do feel call of dutyish style to me.
Multiplayer - if youve played halo 3 youve basically played halo reaches multiplayer. the class system with diffrent bilities pertaing to each are an interesting element and invasion is fairly fun even though it does seem the covent have a dis advantage on some maps.
Basically its a fun game entertaing and it will keep you occupied but it feels like halo 3 in alot of ways which doesnt detract from the game but doesnt help it its not a groundbreaking must have and if your not a hardcore halo fan it might not appeal to you