Pros
I think BNP Paribas has masses of potential to have the best possible working environment in Investment Banking in London. Senior management seems to endorse initiative and have a good and sensible ambitions for the bank. I've met and worked with some of the nicest and most friendly people of any job I've ever had in Investment Banking in London. Its a casual and friendly working environment. Close to West End, good gym, good canteen, close to Regent's Park. An idyllic location away from the hustle and bustle of the City and the Wharf.
Cons
Unfortunately the vast and growing layers of middle management seem to destroy morale, hinder progress, and celebrate incompetence at evey opportunity. Instead of investing in technology and in empowering its staff, BNP Paribas seems to have started hiring many of the dregs of middle management from other failed banks (at great cost) in the wake of the global financial crisis. This has served to squash opportunity and frustrate anyone who has good ideas or potential.