Aside from lacking robust online options and a few clunky menus, Lethal League is an amazing package. It's my personal favorite of the revival of couch co-op games, and may be my favorite "tell a friend" game of all time. I know I'll be spreading the word, and maybe even one day we will be watching streams of high-level League play. Team Reptile really hit it out of the park with this one.
Overall Hearthstone is a lot of fun to play, and has potential to be a game that stays around for a long time. While it may not be as complicated as an actual collectible card game, or have the appeal of showing off your collection to your friends, it is a great videogame that has minimal issues and is in a neat package, so it would be foolish to try to compare it to something it's not trying to be.