Gotta say, I'm loving Isaac. It's just the right balance between random elements and skill, if that makes sense. You never know what kind of build you'll get, there's constantly new stuff coming at you as you play... it's a game that's a pleasure to replay. 15 dollars well spent.
However... Edmund, I love ya man, but fuck you with all this toilet humour. There's a trinket that does nothing but makes you fart when you pick up a coin, for fuck's sake. This game is shit. I don't even mean that as an insult, it is literally shit. And piss. And farts.
EDIT: Got Lisa: The Painful RPG (and the DLC and the OST) for just four euros, saved over 10e on it. Niccccccccccccccce.