In short ram at the outside:
Content is much there, that there are quite a lot of cards that are all very different and also more recent opponents, who you might not know from older parts.
The withdrawal comes ultimately from the fact that it's just too easy viiiiel. I have finished the first run with more than 100 life income and am really just at the very last boss sweat.
In this respect: Those looking for a real Challenger, they will not find probably because the find 3 special hidden coins on each map has also not proved to be really hard;)
