I actually enjoy this game. I've played the other Mystic Mansion, and I have to say I prefer this over the other.
I consider these my "mindless" wind down games where I want to do something, but... not really y'know?
I play this as a f2p, as I try to do with most mobile games. Yes, there is the cash shop, BUT there is plenty of opportunity to gain things in the game without spending money. Maybe at most 30 seconds to watch an ad, but you aren't forced to do that. To be honest, it's generous in what it gives you.