I went to the One Stop Thali Cafe with a couple of friends, both of whom are aggressively carnivorous like me, and we really enjoyed our meal - in spite of its meatless bent. The dhal in particular is absolutely excellent. We had the taster platters, which give you a selection of thali dishes. Everything we had was very tasty, particularly the cheese-based dish (I was chomping at the bit for protein). The atmosphere is great - service was slightly slow but pretty friendly, and I love the decor. If you've spent some time in the Stokes Croft area you've probably seen this place - it has a really distinctive exterior, and is just as colourful inside. It's obviously very popular with locals, is very reasonably priced, and I'll definitely go there again. The atmosphere is vibrant and the tables are packed in quite tightly though, so I wouldn't necessarily recommend this for a romantic dinner date.
Oh, they also do great takeaways; you buy the takeaway containers the first time you use the service, then just bring them back next time you want a takeaway. Perfect!