As an employee of Hashicorp, I'm very excited for this change. Not that Mitchell was anything less than a great leader—on the contrary, I thought he was excellent. It's just that he's also got such a great ability to identify the right abstractions when tackling a problem. The fact that he'll be "in the trenches", so to speak, gives me even more confidence that Hashicorp will continue to make tools that strike a nice balance between power and simplicity.
Frankly, I love it. The attitudes that have made the open source community welcoming are the same ones that permeate the company. Generally speaking, people are very friendly and helpful. That said, it's a job and your mileage might vary. Personally, it's the best place I've worked, and I don't plan on leaving for many years.