I liked this place, on a whole, but I think it doesn't stand out too much from the pack of vegan/vegetarian Asian restaurants in the South Bay.
We started off with a "matginder's spicy bbq drumsticks" ($5.75) which were the standard variety of vegan chicken wings you find in this area; they were covered in a pretty tasty tomato-bbq sauce and came together well. Apparently the owner named this dish by combining two of her regular customer's names.
For our main course dishes we had a "delightful green noodle" with tofu ($7.75) and a "lemon grass veggie chicken" ($8.95). The green noodle dish sounded great in theory, but ended up just being a regular Vietnamese stir-fry with a semi-sweet sauce. The noodles sounded great (made of some type of ancient Egyptian plant), but didn't taste all that different from any other rice-type noodle.
The lemon grass chicken was more impressive: just many pieces of firm vegan chicken covered in lemongrass. The lemongrass flavor on this dish really stood out and I'd recommend it. We got it with brown rice, with cost an extra $1.50 (I hate it when places charge for rice, but at least they offered brown rice and not just white).
For dessert we had a "caramel flan" ($2.50) which was basically silken tofu in a caramel sauce. It was really good. The low price was nice, too.
The service is friendly. The decor on the inside is pretty utilitarian, so it's not the best date spot, but Happy Bamboo is certainly good for a simple and tasty vegan or vegetarian meal.