Pros
Work life balance can be good, at least sometimes. Office location is great. Free drinks, company trips. Compensation can be good when market favors.
Cons
If you are a graduate, and intersted in market making, this can be a good firm for you to learn. Technologies used are very limited, not fantastic. After some years, you can decide if you're really interested in this area and probably you still can find another job in the market (although the skills may be not that marketable). Some senior folks are not that friendly and makes you feel terrible. For example, may be talking something completely wrong without knowing it. And they stop you to challenge it. How would you feel if your 'manager' is like a kid that doesn't know the programming basics? Besides this, insulting words and personal attacks are something you may feel during work.