I have spent a significant amount of time with the Gears of War 3 beta already. Though, I have only been able to play Team Death match and King of The Hill ("Annex" is no more), I can say as of right now that this may be the best Gears multiplayer experience yet.
First of all; anyone who plays online with me knows that I have been sticking to only single player experiences for awhile now, and kind of fell off the grid with playing online. The Gears of War 3 beta changed that. Anyone who also plays online with me knows that I'm a HUGE fan of Gears of War multiplayer; both 1 & 2. I've always choosen to play Gears of War online rather than both Halo and Call of Duty since I prefer the slower paced; more tactical approach (though some may argue that Gears just becomes a shotgun battle).
The Gears of War 3 beta feels a little faster than the past two installments, and the cover system seems to feel better than ever; thanks to the fact I'm not sticking to EVERY wall I run into. The new weapons like the Retro Lancer and the Sawed Off Shotgun have a great feel to them and are a perfect fit. Other new weapons include the One Shot and the Digger Launcher; which digs underground towards an enemy hiding behind cover. More powerful weapons such as the Digger Launcher and Sawed off shotty suffer the lack of ammunition and slower reloads in return for their ridiculous power to help even out the battlefield. The new maps are all large enough, and have some great vantage points. They all look great and I honestly can't wait to see what else the full retail game will offer.
All in all; the Gears of War 3 beta is an awesome experience. Servers are more dedicated, the game feels faster and more fluid, and the new weapons add a new experience to a familiar battlefield.