I think your experience here will really depend on when you go. We went on a busy Saturday night, and when walking in were greeted by the whole room (mainly drunk "lads" on stag dos) chanting "you're not f-ing welcome!" We walked through and battled to the bar for drinks, then headed into the basement for he dancefloor.
The place was rammed to capacity, but we managed to find a small spot to dance. Everyone there was annihilated from drinking. At one point, we had the experience/horror/hilarity(?) of watching two guys stripping naked and performing sex acts upon themselves in full view of the dancefloor. Most were competing to out-lad each other by chanting, doing push-ups on the floor, jostling around, pushing people out of the way etc. Essentially, the place is full of young, rowdy men competing to impress other young, rowdy men. Depending on your idea of a fun night, or general experience in nightclubs, you may find it too much.
Despite all this, our group kept to ourselves and had an fun night. The music was great, the drinks were good, and we had tonnes of fun (thus the 3*). It was an interesting introduction to Prague nightlife, which unfortunately has become a hotspot for laddish binge-drinking despite how beautiful and cultural the city is.