Pros
Working at GitLab is like getting a degree in remote work. They are relentlessly committed to writing things down and reinforcing asynchronous work. Once you've experienced having the entire company using the same tool to communicate and collaborate on work, you won't want to go back. By focusing on results delivered instead of time spent on work, you're free to make your own hours and get things done without being micro-managed. Pandemic aside, there are some fun opportunities to travel and meet up with teammates around the world.
Cons
Scale makes everything harder, including maintaining culture and practices. People coming from more traditional workplaces default to busywork and lots of meetings (no shade, it's what a lot of people are used to!) instead of being thoughtful about what deserves time and effort. There are many layers of the org to navigate to get anything off the ground, and the tendency now seems to be toward inertia rather than trying creative new things. Salaries are not competitive now that so many other tech companies are remote and offering SF base pay. At this scale, individual successes and achievements are more highly valued than collective ones. This isn't wrong, but doesn't feel great for those who joined the less mature company which had less of a focus on personal bonuses and being "key talent"