Pros
Great mission and core values, and great products. I gained a lot of good experience here and the engineering teams are full of wonderful, skilled, and knowledgeable people.
Kontras
I had a terrible boss, which ruined my experience at Hologic. He was inappropriate from both engineering and social standpoints, and made project-ruining decisions on a daily basis. Despite efforts to work around this, he influenced my work significantly, often preventing me from doing what was needed for my projects, blaming me for failures, and generally making day to day work miserable. It got to the point where I was frequently overwhelmed with just the prospect of going in to the office (I did anyway). Upper management and HR did nothing to mitigate this despite several complaints (from me and several others). Be careful who you hire in with, as lateral movement is difficult (if not impossible). Culture is very corporate, which can be good or bad depending on what you like. Cross functional teams could be better organized and there are a lot of small day to day frustrations, though there are people who push for improvements and are committed to efficient product development.