Long hours. They have something called Flexible Time Off rather than statuatory holidays, and you don't always get enough or same amount of time off as you might in other places. Burning out is a risk.
No career opportunities, especially now that there's no internal mobility. The area I am in is very clichey, which can hinder any opportunity or recognition if you are not considered one of them.
Under-performing teams and people are not dealt with and given the appropriate training or development. They become a real burden, which increases the workload, hence longer hours. It's not enjoyable having to compensate for them constantly.
My experience in BlackRock Finance has so far been poor. I was not treated well, especially for the first 18 months. It become marginally better when I started looking for other roles internally, i.e. a bad employer is like a bad boyfriend, he only starts paying attention to you when you start leave. However I do believe that it is localised to this area and I know other teams are good to work in.