Pros
The Broad Institute is fantastic. You work with smart people (this place grew out of the human genome project!) and you get to work for a non-profit making the world a better place without having to worry about long-term stability. The work-life balance is fantastic and the amount of vacation time is fantastic. Supposedly the pay isn't as good as the standard for software engineers, but that hasn't been my experience. You get to learn things in a totally different area while also working for a place that has a history of good software engineering. It's also the most diverse group of software engineers I've seen in my life. It's a rare thing in the world of software development to find something you can feel this good about working on. Plus people are very nice; I think it's because the Broad naturally attracts people who want to make the world a better place.
Cons
Salaries are probably not totally competitive (but the vacation time is incredible: 12 paid holidays, closed so you don't have to use vacation time from Christmas to New Years, starting with 3 weeks of vacation your first year and then 4 weeks after that). Because it grows so fast, expect to move locations a fair amount. Sometimes you can feel a little isolated from the broader organization, although not as much as you might think. The big one is that there are sometimes unusual constraints because science and medical research are significantly more regulated than tech and have a different culture (depending on what you work on, you may have to heavily modify agile). A lot of the software engineers work in open offices (low-walled cubicles where you can hear everyone).
