As a whole, Gears Of War is a great game but the boss battles are a bit disappointing.  There are five boss battles in Gears, only one of which, truly shines.  Note:  I do not consider the Seeders bosses.

Boss Number One, Two And Four:  A Berserker.  You encounter this variety of Locust on three separate occasions.  I believe that the second encounter with a Berserker, is the best boss battle in the game.

Boss Number Three:  A Corpser.  It's an amazing thing to behold and at first glance you find yourself wondering just how it is that you will ever be able to defeat it.  However, the Corspser proves to be a foe that is easily beaten.  The Wretches that appear during the battle, pose a greater threat than the Corpser.

The Final Boss:  General RAAM  RAAM, is no pushover.  He's hard to kill and he's deadly.  However, as final boss battles go, this one is rather disappointing.  It does not feel grandiose or Epic and that is precisely what is needed, to properly finish off a game like Gears Of War.