Pros
Flexible working policy means you can literally work wherever and whenever you want. Also, you're generally given a lot of autonomy to do your work how you see fit. However, this can also mean a lack of support and being detached from your co-workers.
Cons
Atmosphere is like a morgue due to the amount of people and business leaving the door. People who aren't particularly good or motivated get away with murder as no-one really manages them properly. Don't get fooled by the flashy expensive office - you'll find that it's empty most of the time and to be honest I doubt they can afford to stay there much longer. Clueless senior management. Awful decisions being made, with no thought about the consequences for their teams due to the fact they don't have an idea what is going on below them and/or just don't care. Good people have left because of this. There have been some cringeworthy announcements where they've obviously obsessed on how they should communicate to the company and failed spectacularly. If they actually cared, they would have already known the right way. The so-called "leadership team" is a closed shop and they quite simply only care about how they're seen by people above them and don't actually lead. If they continue on this path, the company will cease to exist in a couple of years.