Pros
As an engineer, I love Etsy's culture of curiosity. While industry standard best practices are of course important and are the standard for good reasons, it never hurts to explore and experiment with alternative approaches. Having experienced Etsy from an inside perspective for over a year now, I can definitely attest to the increased freedom, benefit and satisfaction from exercising the curiosity culture in my day-to-day work. As a human and just "I want to work so I can live my life" perspective, Etsy's benefits, culture (not necessarily just engineering culture), work-life balance and many other aspects hit the spot for me. Etsy is definitely a people-oriented company and while all the initiatives and projects ultimately reflect that people-oriented mindset, it also reflects nicely in the company culture for employees, too.
Cons
Purely as an engineer, there's just one relatively minor point. Having started as a small startup back in 2005, there are definitely remnants of a bygone era of "wild west coding" at Etsy. New code that gets churned out nowadays is honestly fine, but it's not entirely rare to come across a codebase that has a lot of legacy code in it still. With some of the shakeups in the past half a year (As of November '17), there've also been some re-orgs and while it was overall positive and a great change in my opinion, naturally there are still some kinks to be worked out. That said, I want to keep it clear that the above two points are actively being worked on, at least within the teams I interact with. They're just points to keep in mind given recent events.