The thing that sold me is the new Road to Legend app that FFG released for iOS and Android.
Normally, Descent is a game for 2-5 players with one of those players taking on the role of the Overlord. I've never been a huge fan of these sorts of games because they rely on one person to lose for the cooperative team to win. If the one person wins, everyone else loses. I've always though that games should be either fully cooperative or fully competitive. Finding someone who is willing to be the Overlord and potentially lose over and over can be tough.
Road to Legend takes the place of the Overlord. As you navigate a dungeon and open doors, it tells you which map tiles to put down, where to put the monsters and where to put various objectives and search tokens.
When it comes time for the players to take their actions, you simply tap your characters icon and click End Turn once you're complete. One of the monster groups will then activate, with the app telling you what they'll do. It's important to note that the monsters will do different things from turn to turn, presumably either based on a round based script or on some other trigger.
You won't necessarily see the same critters from play-through to play-through, either. The app has a section where it allows you to check off the various products that you own. Based on this list, the app knows what monsters and tiles you own and will build missions for you accordingly.
My friend and I played through the tutorial mission and then the first two side missions. It was tons of fun not knowing what was going to be behind a door and not knowing what monsters were going to pop out. I've played a lot of Imperial Assault, which is basically Star Wars Descent, but have only played as the Imperial... which is basically the Star Wars Overlord. It was incredibly novel being able to just enjoy the game without being responsible for maintaining the mission and the monsters.
So, as I said... I'll be purchasing the core game off Amazon later today. Retail is 80 USD, but it goes for around 70 USD online just about anywhere. It's the only thing necessary to use Road to Legend.
Definitely check it out.