This sounds a bit like party dynamics, not class. We had a GWM vengance paladin during STK - with several other melee characters - and he was MVP in damage.
My PC hasn't got GMW - I took a Str bump at level 4, though I've got GMW pencilled in for when i hit 8th at this point. The problem I'm having with being a melee character in this campaign is fragility. I've got lots of hit points (house rule is max hp for the first 5 levels), but a single frost giant can still take me down to half hp in one blow, and a melee character can't play shoot-and-hide-behind-a-house like an archer can to avoid getting hit back. There is a party dynamic issue contributing though - being the only melee character in the party means that if i do wade into combat, I'm usually doing that alone and I'm going to be the target for all the attacks coming back the other way.