Pros
Atlassian is a great place to work. I come into work every day looking forward to it, and my colleagues are also my friends. The company lives its 5 values every day in everything it does. The work is challenging and interesting, there are great perks and events, and I feel like Atlassian cares about its staff which makes for a low attrition rate. Atlassian learns from its mistakes, and although you can feel the bureaucracy creeping in as it grows from being a startup to a mid-size global company, I feel like there has been a lot of progress in the last year to address some of the problems addressed in other reviews. The work/life balance is exceptional, better than any other company I've seen. People are actively encouraged to take time off and not stress or work outside regular hours to prevent burnout. Atlassian recognises that hiring and training people is an expensive and time consuming exercise, so it tries to keep its staff happy.
Cons
Sometimes it feels like management is comprised of a lot external hires who don't get the company culture. However it's definitely getting better as these people start to fit in. A lot of Atlassian's products are very old with legacy code bases, and some teams move very slowly especially with people constraints. This can be annoying when you want to ship awesome stuff to customers frequently. The perks are fun and frequent, but there could be more attention to detail to the office environment. Atlassian spends a lot less than other tech companies per square meter on office fitout, which means our offices don't have as many features you might get elsewhere.