Pros
AI2 is doing, frankly, super cool research and engineering. The challenges AI2 is tackling are relatable and useful -- you won't find ambiguous, directionless, or opaque research going on here. As a side effect I'm excited to explain what I'm working on here to friends, relatives, and colleagues, something I can't say about other projects I've had in huge tech companies. I find the culture here to be diverse, welcoming, and inclusive. Everyone's input is valued and individuals are given great autonomy, though you are rightly expected to match the team's self-starting and never-stop-learning attitudes to thrive here. It's a very energizing environment to work in because the team is open, passionate, and engaged both in the daily details and in the longer term goals of AI2's projects.
Cons
AI2 has some of the growing pains of any startup, but they do a good job addressing them directly and transparently. There is definitely a bit of a "lunch desert" around the building as other reviews have mentioned, but the immediate neighborhood is under a lot of active development (a very up and coming area).