Pros
What can I say Express Scripts has really turned things around. I joined the company with a lot of anxiety and now that I have been here a while I absolutely love my job. No seriously I turned down Google for an engineering manager interview today without thinking. The company is really promoting an engineering culture that is obsessed with automation and doing things right rather than quick. They have removed roadblocks on new technology, and compliance that you typically see in huge fortune 100 companies. Schedules are quite flexible depending on your manager. The projects are very interesting especially as we transform with lots of ability to really make an impact quickly. Embracing agile has promoted work life balance (if you want that) or if you want to work more projects you can get involved with other teams.
Cons
There is lots and lots of ambiguity meaning that you have to be quite good at just driving in a direction and expecting that you may have to backtrack. Building an engineering culture is hard especially when you are dealing with the past leadership teams mistakes that allowed the company to be known as one of the worst to work for. The company is still heavily network driven, ensure that you are promoting technical leadership rather than the good old boys style of leadership that earned us the worst company title. Be wary of transformation hold outs, if you interview ask heavily about what the team is doing to embrace the transformation. If they don't know what your talking about I would run the other direction. Oh yeah there's also only 6 holidays which is terrible, but 20 days PTO so oh well.