Pros
Atlassian is a company with heart, for sure. In my time there, I never questioned if the values you will hear so much about were just recruiting gimmicks or actual living breathing tenets to live by. There is a legitimate interest in doing work the smart way and being a great company to work for, Like in most good companies, it is really the people who make or break the place and Atlassian has done a great job of attracting and hiring good people. If you are coming from a more "normal" company, the perks at Atlassian are insanely generous. If you are coming from a Silicon Valley software company, they may not stack up to you expectations, but you will still appreciate all of the work the Workplace Experience team puts into making the offices and events the best they can.
Cons
There is a major disconnect between leadership and the people that they lead. I often heard our VP say "all the right things", but never saw any of those ideas put into action. I believe that this is the result of a few different factors, but they can all be summed up by saying that leadership seems to be happy judging their success by what amounts to be made-up metrics and just leaving it at that. In my department, at least, no one at any level of leadership seemed to have a very good grasp of what the operational realities were and none of them seemed to care to either and that is the part that kills me. There were a lot of interesting ideas, but no real care put into understanding the current situation when coming up with a plan to implement them. Right before my departure, a major change in operations occurred with less than an hour of training and no opportunities for those actually doing the work to provide input. There was a lot of trying to force a round peg into a square hole and then blaming the people on the ground level when things didn't work out. Accountability only ever seemed to apply to the lowest on the totem pole.