White water rafting is by it’s very nature a dangerous sport. Firstly I would make sure that your insurance covers it just in case.
It is dependent on the weather…after the recent rains I would imagine it would be a bit hairy to say the least.
It seems to be fairly professionally run with all safety gear supplied ie helmets and life-jackets.
I did the WWR trip and loved it! It is a long bus ride from the riu complex and thus an even longer bus ride from playa dorada…however it was worth it. I have done WWR in Canada and the DR rapids are very mild. The guides are great, the food is wonderful and the experience is unforgetable. I even got to stear the boat (right into the shore and then backwards down a rapid). I would highly recommend this tour.