I had read about this place on happycow, and have eaten here twice. Was just here in July 2013, here's my Purgatory Pizza review.
It's a kind of "in the middle of nowhere" place. It's not in the busy part of downtown LA but across the river to the east. There's not much else going on in this area except for the metro train stop across the street and some houses.
The place is simple with an old school restaurant feel. You order at the counter, and they make your pizza on the spot - takes 20-30 minutes.
Both times we ordered the vegan "Dave's Junkie Special": vegan cheese, spicy sauce, jalapeno peppers, green peppers, Fieldroast Italian sausage, mushroom. The first time we ate there, our pizza pie was piping hot, and I burnt the roof of my mouth. But it was yummy. The second time we ordered it to-go, but I managed to sneak bites while in the car. the second time around the pizza tasted okay though I thought I smelled meat scent. The kitchen likely uses the same prep area and utensils for making meat & vegan. The leftover, however, seemed to taste even better.
Call ahead to order so your pizza or calzone so will be ready when you get there.Pros: vegan pizza, vegan calzone