Hyper growth is challenging. When you have a company with over a thousand people too much freedom can lead to chaos. Also, the fact that autonomy is one of the core values of the company has turned teams quite selfish about their own goals. Cross team collaboration is almost impossible. It's so hard that ends up discouraging people from seeking to fix or do any task that involves other teams.
It's like living in a country with different factions that pretend to collaborate with one another. The company is divided into several cliques, and the old employees act as tribal leaders: don't even think about disagreeing with them.
It's an EXTREMELY political company. If you hate politics, don't bother joining. It's as political as any big old organisation out there (or worse than most).
Most leads are quite young and with that comes a huge ego. You will feel like going back to secondary school sometimes. Dramas, gossip, etc. It's a downside of having so many young people together.
On the engineering side, it's the most unproductive company I've ever worked for. Anything that took 1 week anywhere else in TransferWise takes 4. Loads of talking, convincing and trying to understand a codebase that has become a huge patchwork of badly designed APIs, very little actual coding. Code quality is average at most. Be prepared to deal with technical debt through the roof. Because the company grows so fast, most of the engineers know very little about the current codebase. No documentation, no javadocs, just hearsay.
Last but not least, the perks of being a vibrant startup are mostly gone by now. This is a huge organisation not a small startup anymore. You still get some of the basics, like free fruit etc, but it's the same as you get in any other tech company nowadays.
