The sheer amount of content, reworks, secrets, changes, etc. are fucking ludicrous with this "expansion pack". Repentance is basically a new game with the same engine. I don't think I would recommend it to isaac newcomers, as some of the changes are particularly unforgiving, and 60$ is a steep up front price. But if you're even considering repentence, something tells me you arent a newcomer.

Edit: I dead godded! Buy this game