Pros
Slack is full of highly motivated, smart, empathetic employees who look to build on each others strengths and make amazing products together. We live and work in the Slack product so we are dogfooding all day, every day. We want to make work easier for our users and live the mission. The company is grounded and centered in the best outcome for its users and support its employees (especially during the challenging times of covid-19), at an impressive level. Slack might be based in the Bay Area but it lacks some of the bad reputations of other tech companies in the area. A breath of fresh, exciting air!
Cons
We work hard and some people work long hours but it comes from the drive and motivation of the product and is never forced/required by upper management. I really can't think of any other cons!