OK, this may be a German thing. But I totally disagree with the other experts.
For any important meeting, you would prepare, take some notes, and take them with you, just in case you want to look something up, confirm something, or just get momentarily stuck. Why not an interview?
I can't see anything wrong and certainly wouldn't hold it against a candidate if they brought a page with some questions they want to ask, maybe some key facts about the firm. Some firms share names of the interviewers before the interview, maybe look them up on LinkedIn. Don't create stalker-style profiles, but some key facts like Alma Mater, interesting previous jobs, tenure with the company...
To the contrary, I would view it as a plus if an interviewer is well prepared (if he or she is not too anal about it) - because that is what I would expect a consultant on my team to do!
It would probably be a bit much to bring case specific things, like a framework cheat sheet, or some figures that seem important.
But other than that, where's the problem?
But again, this may be a German thing. We also have a saying "Wer schreibt, der bleibt." You can look that up ;-)