Pros
Pay and benefits are top notch. If you go above and beyond, you will be recognized with huge bonus and huge base pay increase. Full family insurance paid with no employee contribution and a medical doctor in the building you can see for free. Incredible yearly party where a whole island is rented out with amusement park rides and free food -- great for family. Company really does good for society -- e.g. if you volunteer 40 hours, there is a "dollars for your hours" program that can donate $5000 to that charity.
Cons
Technically, seems sort of behind. Half the code base is Fortran. Bizarre restrictions on things like Boost. Low level C++ libraries are high quality, but higher level code is a mess. In many teams, you might spend hours each week just trying to get your code to link because all the libraries are changing underneath you all the time. The databases and GUI are bizarre proprietary stuff that are a pain to use and these skills are useless outside of Bloomberg. The email and proprietary issue tracking systems are terrible, with basic things like word wrapping not working reliably. If you like finance and high salary, you might look past these shortcomings.