For a cafe attached to a museum/attraction, Cafe Phipps is like a 4.5, if not 5-star establishment. In comparison to eateries in general, the food is fine but not outstanding.
I love that the cafe uses local, in-season ingredients, and that it composts much of its waste. Currently, it's one of two Pittsburgh eateries certified by the Green Restaurant Association.
Right now, the cafe has Friday happy hour, from 5-9 pm, which it calls "Agave Nights," in honor of the giant agave plant now at the conservatory. $4 for margaritas, and $3 for beer, and popcorn shrimp or chicken nachos as food specials. You can also order off their regular menu (which changes seasonally) up until 7 pm.
The falafel which is currently on the regular menu comes like a burger--as a single patty, on a bun. The bun would have been better toasted. I don't know how I felt about the blue cheese dressing on the patty, as opposed to a more traditional yogurt sauce or tahini sauce. The cole slaw side was good in that the cabbage and carrot were fresh, but overall the slaw was too liquid-y and the random pieces of fruit (pineapple?) was rather strange. I've also had a mushroom sandwich of some sort in the past here (not on the current menu), which was sort of bland.
I wouldn't eat here unless I was also visiting the conservatory (which I really do recommend), but this is also one of the healthiest places to eat at in Oakland, and probably has the nicest atmosphere of all Oakland food places.