Whats amazing is when you have 6 hearts before you even leave the first floor (+ 1 silver heart, if thats the name for the temp ones.)
Edit: Completed that run, (execpt i dont have the new levels unlocked (but have defeated mom's heart before)
). I also unlocked eve that run getting The pact and the vis-lazer power up from the devil. It pretty cool becuase i managed to still end with 12 heart containers.
Anyway started a run with eve, i've only got 1 extra heart container so far. And its been prity scetchy with the items, little heath and weapon upgrades (excluding range) and have also obtained alot of speed. Whish me luck!