I was in the DR a little over a year ago.  Didn't go to any of the adult resorts.  Women are fantastic though!  Be careful you can get in some trouble.  Again don't have any expereience with the adult resorts......

Different experience

Hesitate to even respond to this ... with all the BS responses here.  I have been to a number of the DR places.  If your looking for a few days of R &R it might be a good option.  The format varies widely.  Some you pick a girl for a day and you can change after a full day and night.  Others you just grab and go each time you wanna play during the day.  Some you pick a girl in advance and then she is with you for the duration.  
Most of these places are very nice.  Some in private villas, some in public hotels.  
If you like variety, I would suggest you not choose in advance.  A bad pick makes for a miserable vacation.  Trust me ... I know.
I would also strongly suggest that you think carefully before going to one where you are a guest in a regular resort.  Remember there are often kids, etc. in these resorts.  Many regular
people staying there will give you the evil eye.  Especially the other females.
The girls range from locals who are drop dead gorgeous to not so much.  Other resorts are filled with Eastern Europeans so are almost all model material but often not so friendly.
So my friend, variety is the spice of life.  Choose well..