Best game of 2006. Easy.
The Action reload feature is a great bonus, it can make or break you in an intense firefight. The variety of weapons is sufficient, but all I really needed throughout 90% of the game was the Rifle w/ the chainsaw attached.
The only downsides I can think of is that the environment is basically all gray/brown colors, there is not much difference in the color contrasts. This is probably fitting considering earth has supposedly been overtaken by the Locust, yet it would be nice to have a tad more color to look at while playing. Also, the campaign seems like an average length for a shooter, yet for such a great game, it makes on sad when it does come to an end.
All in all, Gears of War ranks right up with the best shooters that I've ever played, and is well worth the $60 price of admission. It is one of those games that makes you want to go out and buy a 360, if you don't have one yet.