Pros
The biggest relief and the greatest advantage I felt about working in this place was the fact that there is not email mess in the company. Everything happens via Wiki (of course Confluence) and believe me, it's a real benefit. So easy to find content and people who can help you in any area.
Cons
Due to the growth many people have become managers who has no clue about people management and trying just to do micro management in every aspect. Their ego seems to be driving people crazy and resulting in people quitting jobs. Lateral hires who have no clue about software and just having management experience are trying to build teams. That's going to fail. Using authority for decisions only build resistance towards decisions. Absolutely no way to switch roles even though there are lot of lateral hires coming in just because they have a big brand in their resume. Salary was pathetic as the brand value of Atlassian is expected to keep the employees happy. Regarding other perks, how many beers, pizzas and candies can you eat in a day to compensate for that? While developers were being paid less, we had a team for QA (whose role I have never understood till now) who were being paid a hefty salary which used to de-motivate all of us. It's no more a startup, so hierarchical that I wonder how such a small company can have 6 levels of reporting for 600 employees, while big MNCs with thousands of employees are able to manage with 5-6 reporting levels. But having said all these, I would still say Atlassian is good place to in.