I worked for RBSC in France and Belgium from 2004 to 2007. So let me try to answer your questions from an inside (and hence maybe a bit biased) perspective. The firm understands itself as a generalist consulting firm which means that is serves clients of all industries with regard to all kinds of problems. And this is also the situation in the major European markets where they primarily consult large corporations and governments. Nevertheless, there are regional differences. In Germany, for instance, RBSC is doing a lot of restructuring assignments as well as lots of marketing and sales projects. In France, there is a lot of work in the aerospace and defence industry. And in the UK, RBSC used to mainly consult in retail and manufacturing. At the time when I left the firm, they also heavily grew in financial services and in the ICT industry - don't know what the situation is like today in the face of the crisis.
There is no such thing as a general consensus on the culture of the firm since opinions on the culture differ quite a lot. What is probably common across all offices of the firm is that people are really hard-working, intelligent and entrepreneurial. However, there are considerable cultural differences across the different offices/countries. The offices used to work quite independently from each other for a long time, which has resulted in slightly different local cultures. For instance, in Central Europe, everything is way more formalized than say in Southern Europe.
Meanwhile management has understood that they need to globalize knowledge management, people development and account management in order to fully realize the firm's potential so that things are becoming more and more similar across the different locations - especially in Europe.
Pay is definitely comparable to MBB - if not even higher in some countries.
I personally think that RBSC is an excellent place to work at for a couple of years since you get a lot of responsibility early on, receive absolutely competitive pay, and work on top management issues for classy clients.
And in most European countries (maybe except the UK), their reputation is definitely on par with that of MBB.
To wrap it up: The firm is definitely worth a consideration when you want to pursue a career in strategy consulting in Europe.