The Binding of Isaac: Rebirth

Judging by this topic and a lot of stuff I've seen this is a lot better?

Oh it definitely is, however, I would say you won't get the full feeling of how much better it really is unless you've played through enough of the original to unlock Platinum God, or at least close to it. They more than doubled the steam achievements between games so that should give you an idea of how much more there is to do in Rebirth. Not to mention it isn't coded in craptastic Flash, which is a huge plus in and of itself...