Pros
Atlassian does a lot of things well – Internal documentation – technical, semi-technical and informal blogs that provide new folks with context on past decisions, and keep the fast-growing company feel less sparse. A design-engineering-product triad model that encourages a high trust between various function, and greater ownership with YBIYRI. A healthy work culture, opportunities to work with and learn from Atlassians in other locations. Some really good mentors (you just need to ask!)
Cons
The current office location (Eco-world) makes work-life balance a harder for those who aren't staying close by. By no means is the traffic an Atlassian-only problem, but when you've to spend 45 minutes to get outside the tech park (10 mins by walk) only to further get bottlenecked by the ORR traffic outside, it kills you a little. You'd expect a company like Atlassian to give this factor a little more importance than other companies, who either oblivious to it or have given up.