The review are mixed, but don't worry -- it was because earlier every players had to have this dlc to play the "premium" modes. It was quite ridiculous to have to ask all your friends to buy this only to play 2 different modes.
Currently, they reversed those changes. Everyone can join premium lobbies, but you need this DLC only if you want to make your own premium lobby.
Those two modes are simple, but I really enjoyed them so far. It's not too pricey and always fun with close friends. I definitely recommend it to people that enjoyed the main mode.