Pros
A great place to work for folks who want to make a difference (part of the profits goes to Bloomberg Philanthropies). Engineers will find a good WLB with all the flexibility they need and a salary appropriate for the finance industry while keeping a clear conscience due to being a neutral market participant. Engineers enjoy a high degree of autonomy and ownership, as well as recognition (the department is firmly the profit center of the company). Curiosity, experimentation and learning are encouraged.
Cons
For engineers, the yearly performance evaluation is mostly qualitative, with the resulting metrics not being shared with individuals. It is thus hard to compare your performance and compensation to peers around the company (it's not openly discussed), but you do get relatively clear direction from management as to how to improve. There is officially no staff engineer role, but there are recognition+extra responsibility programs (tech reps and champs) and the best engineers can find ways to make an impact anyway. Recognition of those efforts at evaluation probably varies though.