If you played only sentinel/marauder and have mmo experience you might think it's an "ok" class. If you roll another class and see how easy it is to do better with it, you won't go back to Sentinel/Marauder. The AC can't do anything better than any other existing class and does not bring anything useful to the group apart 15% buff once every 5 mins. Some say it's a glass canon - yes it's glass, but every other class does same or better dps. Take Commando as an example or sage/assassin - far better survivability while dealing superior damage and providing debuffs on the target, ability to off heal or do massive damage.
The class is not fine when you compare it to other classes. I doubt many want to play a class the requires you to get epic 50lvl gear just to be on par with other classes decked out in greens/blue.