Pros
A bunch of really smart people trying to solve some really hard problems. Not only smart, but pretty damn nice, too. I left in January, and there are still people from there I spend time with, and expect I will for the rest of my life. It was a really, really nice bunch of people. The work there _is_ challenging: they're trying to measure what is essentially infinite space, and make sense of those measurements. That's hard to do. There was always opportunity to learn more, if you wanted to - my boss gave me lots of rope (granted, I likely hung myself a few times, but overall I was able to build ladders with it and climb pretty high in some new skill sets). I left there with a ton of industry contacts, expanded skills, and a pretty deep insight into how a company functions. That's not a shabby take-away, and more than you get at a lot of other companies.
Cons
So. Nothing's perfect - I get that. Not sure if someone else here wrote it, or I heard it somewhere else, but it probably is true that a brilliant, but heavily focused on tech, founder/ CEO let himself fall too in love with his solution and not with the problem he was trying to solve. It's a classic trap - personally, I think Yonatan Stearn has a good heart, and cares about his people. I saw that in the way he treated me. I do think he had a hard time managing remotely from Tel Aviv when the rest of the company was in Waltham - it's just awkward to try and do that, although I do respect him wanting to raise his family in his home country. Markets. I wondered why we pursued some markets, abandoned others, then tried to recoup, etc etc. I think this came more from the problem of having too many options with what to do with the data - we never felt incredibly, deeply focused on one bright goal. But, I'm not a business visionary, so take that with a huge, heaping, maybe even pile of salt.