I cannot give this less than five stars - the game is brilliant in its simplicity.

However, the rules leave much to be desired; you need to develop your own scoring sheet; it's undefined when you can swap in cards from the expansion, and if so, how many.

Eventually I wrote up my own beat your average (not your high score), to allow a swap with the 1st expansion. When the 1st expansion is depleted, swap in with 2nd expansion. Even so you would never have a game that combines base with 2nd expansion cards. In other words, the  whole expansion concept needs some rethinking. 

Plus there is a fan  created 4th expansion, sadly locked behind bgg.