Long story short: food was only okay for me, but the others, including another vegan and one vegetarian (and two omnivores), enjoyed their dishes. Service was TERRIBLE.
I had a pretty bad experience at Cafe Poca Cosa, but don't let this review spoil the place for you. Most of the people I know really enjoy it, and it's actually a pretty nice restaurant inside (there's even free parking on the corner across the street--at least it's free at night).
First of all, we made reservations a week in advance and put in two vegan requests. When we arrived at the restaurant, about a half hour early, the hostess inside insisted we put our names down on the call sheet. We did so, explaining our reservations, and were told that if the entire party wasn't present at the time of our reservation, we wouldn't get a table. We asked if at our time we could have the table and then save a seat for our reservation-included friend if she wasn't there on time and the answer was no. Luckily, she came on time.
After this incident, a waiter treated us with distaste (we were a young party, but not rambunctious, and we did not order alcohol), complaining loudly to the hostess about how we had "toys," (we were celebrating the birthday of a friend and she was looking at one of her presents, all contained within a bag and not all over the place), and every time he passed us he rolled his eyes, sucked his teeth, etc.
Anyway, the food. Sorry. The customer service experience was just so bad I couldn't help myself. The food I did not enjoy. The vegan dish was almost ALL spring mix. I could've bought a $2.95 bag of it at the grocery store instead of paying $25.99. Also, for those who are annoyed, a large section of the place is an inedible garnish (in my case, a pineapple top). I thought the plate I got (a tamale with vegetable puree) was very sweet (though I've heard this is preferable). I looked at the non-veg plates and saw a lot more food, however.
A few plusses--the tortilla chips served as a freebie are really good, and it's nice to get a giant bowl of rice to share with your companions, but an additional small plate for each of us would've been nice (or I guess they could've tossed the worthless garnish for the rice).
I also wanted to note that our waiter couldn't confirm the black beans (served family style along with the rice) as vegetarian. It's a pretty safe bet that they were, but maybe someone else can clarify this.
Oh--one other note. Lunches are between $10-15. Dinners are about $25. I've heard lunch service is actually less uptight and pretty decent.