For me it was the multi-use cards which really sold me on it – being able to put the cards in your hand to different uses for different characters in your team, but having to sacrifice certain options (perhaps sacrificing a team member entirely) in order to achieve what you want to do the most.
Plus the ability to choose how many cards to play on a turn, allowing you to build up your hand and then go big on a later turn, or press your luck while you’re running on empty.
And yes, there’s plenty of luck, and sometimes your cards don’t let you do anything you want to do (but in hindsight that can be an entertaining narrative too : )
The game plays quickly, so I haven’t found that aspect to be a problem.