definitely the best in the series
I found the third part to improve on the action especially when compared to Gears of War 1, this is after all strictly a third person shooter and the last thing you want to be doing is killing a few grunts while nothing big is happening.
This is my #1 favorite thing about Gears of War 3, the first game in the series just had you running around killing a few small things while not much else was happening, if i play an action game i expect ACTION, Gears of War 3 provides just that, from shooting a huge sea monster while in a submarine to shooting these big blimp looking monsters (who carry dozens of grunts) while you yourself are riding one of the same blimps.
Gears of War 3 is probably one of the best looking games on the 360, recently i have been playing on the PC which can obviously achieve visuals beyond that of the 360, but even then i could tell that this game looks good.
I have played all 3 games but beyond that i have never been crazy about them, they do not bring anything new to the third person genre, but Gears of War does what it does very well.