I cannot comment about work culture at Deutsche bank particularly but generally speaking from my experience at Barclays and now GS, culture at any international IB is very positive, Macro-managerial, and problem solving oriented.
I am guessing the negative reviews you have heard are about the work-life balance/long hours, is it? Well it depends on how young you are and what you are looking for! You can consider 11-12 hours average, some days 16 hours, some days 8 hours. But you get paid for it!
Also IMO, positives outweigh the negatives tbh, Everyone is hustling all the time and in most cases you are doing way more work than peers in a competitor investment bank! People are very sharp, and generally do not micro-manage! Given smaller teams ,you wont generally have a boss who is up your back side.
All in all, it's a busy life but worth to start your career with.