I recently got a chance to play Defenders of the Realm, and I'd like to share my thoughts briefly.
The gameplay is quite fun. I tend to enjoy challenging cooperative games, and this one doesn't disappoint. The base game comes with a variety of adventurers, and there are several adventurer expansion packs. Most characters have simple abilities that still add a lot to the game. For example, I forget the Dwarf's first power, but his second power lets him re-roll failed dice against dragonkin - the hardest monsters to kill - and his third power reduces his damage per turn by 1, which, among other things, allows him to stay in a spot with 1 enemy at the end of his turn without taking any damage at all, so that he can finish them off on the next turn. I had a lot of fun playing the Eagle Rider and questing all over the board.
Pro tip: The movement mechanics of the cards are a lot easier to understand once you realize that the top-left symbol always ignores color. (Really, the portal mechanics were the most confusing.) Between the character variety and the quests, there's plenty of replay value in the base game alone.