I only ate here because I was in the area and really hungry, so I used Happy Cow to find the nearest veg place. The place doesn't stand out, it's pretty dingy and dirty, but I suppose it's reasonably priced for a place in the backpacker's area.
I had a pretty underwhelming veg burrito (possibly the limpest and plainest burrito I've ever had). However, there was quite a lot on offer for vegans/vegetarians and it's true that I didn't get to sample more than the burrito, so I can't judge how the other food is (perhaps the Viet food is better).
I guess if you're in the area and want something cheap by D1 standards it's okay, but seriously, vegans/vegetarians, get out of Pham Ngu Lao and see what great veg food the city has to offer!!
Cons: Dingy, dirty, Burritos aren't great