It is not actually a fingerprint process. The first time you use your pass you will put two fingers into the machine, slightly push them together, and somehow it stores how hard you have pushed together. It is very simple and is only done on adult passes.
It is more time consuming then it was in the past to get into the park, but not horribly worse. The problem we saw a number of times on our last trip is that for some reason it would let you through one time and not another. When that happened, at least when we were there in October, you needed to show ID. That made for many unhappy people who were not allowed into the park and had to go back to the resort for ID. I hope the kinks have been worked out, but I would suggest carrying some ID to the park.