Pros
Really mission driven company that deeply cares about the customers. Culture is nice and chill, in product engineering teams you can work in a relaxed manner and only few teams will ever challenge you on this.
Cons
Contrary to the expectations you won't find too many smart good performers around you. TransferWise doesn't compensate in the high brackets to attract those while most original employees with high stock packages have left by now. In addition people in engineering teams are almost never let go so you can imagine what environment this creates for the talent pool. Level of technical debt is very high for most teams and it is really hard to develop things quickly. It does not help that leadership team prefers to ignore those problem for most always prioritising features (however minor those are) to long-term fundamental fixing.