Everything. Lower management is terrible, upper management even worse. They don't give a damn about people. Only money and work is important. Forget about good bonuses if you don't agree to work like 60 hours a week - excelling at your job in normal work hours is not enough for good bonus or a promotion. People who agree to do that are praised by managers and put on the pedestal, ruining the work culture.
The work itself in Dynamics is horrible. As a person working mostly on both front-end and back-end, I have learned literally no skills that would be helpful for me outside of MS. Back-end is a bit better but you're discouraged to think out of the box.
Compensation is not competitive considering how dreadful the work is.