All 5 of us in our family have Mummy down as our favorite ride at Universal.
The drop is small by 'coaster' standards, I'd say. I think the launch is more intense than the drop. The abrupt stops are maybe the most intense until you learn where they are and can brace yourself.
Overall, it's not a super-fast ride, but it feels much faster than it is due to the darkness and some 'trickery'.