Earlier in this thread I swore never to touch The Lost as it's too grindy and can't use half of the items in the game and so forth. Then I tried it finally after a 6 month break.
I actually really enjoyed it. It fit my play style perfectly. I always end up taking so many devil deals on every character that I'm practically one hit away from death all the time. And as The Lost you can take all the devil deals all the time. Also you can fly, and you get less boring HP ups.
Having beaten the original Isaac up to Platinum God, Rebirth was mostly smooth sailing for the regular characters. The Lost returned the ridiculously tense runs I had beating
with Blue Baby in the original game. Beating Boss Rush without taking any hits with Epic Fetus really got my heart pounding.
You do need some particular items to fare with The Lost, but it's the same for every characters. Some items are crap and some are really good. It's just slightly different ones for The Lost. It seems you pretty much need 2 out of 3 of Stop Watch, Dead Cat and Holy Mantle to have a chance of getting all the way to the end. But the farther along you can get without them, the more likely you are to find them. It seems many people are playing The Lost by resetting on the Basement until they get one of those items and that does seem really frustrating and boring. I suggest taking it as a challenge. How far can you get with this guy with average items. Don't think about the bosses, they will fall eventually. My Godhead run was me seeing how far I could get with Epic Fetus, as all the guides forbid you from using it.
P.S. I did die about 250 times in the process.
P.P.S. I still think the the Meat Boy/Bandage Girl achievements are kind of bullshit.