It played very much like World of Warcraft, which earned quite a lot of ire from some of the dev team. But where it differentiated itself was with the abilities and their uses, which were original and fun (and you never had more than 10 abilities, some with multiple contextual uses).
For instance, the Sorcerer was a marriage between the WoW Warlock and the Diablo Necromancer, summoning up to eight pets to heckle enemies. You could make the pets explode, dealing acid damage, have them tank targets, sacrifice them for health and cast spells of their own. The Sorcerer himself (or herself) had to manage mana as well as potential backlashes from powerful spells, dealing damage to the player. So it was a balance to try and keep as much power as possible, boosting your own damage (until you floated above the ground with arcs of lighting around you) or potentially got overloaded and shorted out.
It was a fun class, as were several of the other complex ones, different classes delivering different play styles and difficulties. The combat was all about the player feeling powerful, and having the combat feeling tactical and visceral, it was about enemy manipulation and tactical use of your abilities. As a player, you would never fight enemies 1v1, it would always be 2 or more.
When Curt said that the game was not fun, and that we were not playing the game, it was not for lack of trying to play and the last time we all played it we enjoyed it thoroughly. If we had the last nine months we needed to finish, it most certainly would have been at the very least entertaining, if not downright fun.
You can check the videos on Kotaku's page and make your own conclusions on whether the game would be fun or not, although considering how early the footage is and how little there is to it, you might agree with me that there's not enough to make an informed judgment.