I see nothing wrong with the game, maybe you should wait for the game to come out before jumping to conclusions. The Combat was flawed in Origins they had to fix it. Playing as a Duelwielding Rogue was almost impossible because of the stupid shuffling into position not to mention that your allies and other enemies would get in the way. The changes are for the better but I'll wait until the game comes out before I declare Dragon Age 2 a failure which judging by the reviews it's getting, (around 89 average) it's not a failure.
Two handed weapon combat was flawed. It really did need to be faster. Of course, "faster" is relative. Running jumping spinning rolling leaping like a hyperactive squirrel that drank a gallon of caffeine and ate 10 pounds of cane sugar is a little extreme.
The majority of my more than a dozen characters were dual wielding rogues and warriors. It was, for me, far from impossible to maneuver into position for backstabs. Enemies getting in the way worked both ways; one might interfere with my attack, but getting the enemies to bunch up and interfere with each other helped my pc out as well. My party members didn't get in the way; amazing what pausing to manage your party can accomplish.
Granted, my rogue didn't warp from one side of the combat field to the other, and they didn't manage to bulldoze enemies and knock them sprawling, or take the time to do flashy spin-kicks instead of just throwing the fragile glass bottles. But then I never thought that was what a rogue should be able to do. My warriors also attacked one enemy at a time; something I always thought was a restriction of using a sword. I never realized that attacks from a single fighter, using a single bladed weapon directed at one enemy should damage several nearby enemies at the same time.
I strongly dislike the fact that friendly fire is disabled for any level other than Nightmare, due to the new "warriors have aoe effects now" thing. Fighting close to your tank could be bad for your health. As for mages, if you use firestorm or fireball your own party, it should be "A Bad Thing", not just kill the bad guys and not cause major issues for your party. Of course, the limits on the camera probably added to that, since it is now more difficult to target aoe spells accurately. Oh, and the "you can't target an enemy with an aoe spell, you have to target the ground" feature. Hope that not too many enemies will ambush you from ground higher than you can lift the camera. You can't target ground you can't see.
That demo actually cemented my decision to not buy the game. A demo is supposed to help you come to conclusions about a game. It certainly did that. Probably not the way Bioware hoped, however.