Whilst it is very touristy and crowded at places, it is still a very beautiful part of Vietnam. After all I booked this trip with a tour company so I can hardly expect to have it all to ourselves (though it would be nice). Depending on what time you go it will probably be quieter (not sunrise or sunset).
we booked the sunrise, however, we missed sunrise completely because of the jeep picking us up 45 mins after they were supposed to arrive (4:15 am) this was annoying!! Never mind though, it was still very beautiful and my mood soon picked up to the point that I wasn't that mad anymore, mostly cause rising in the back of the jeep while the driver drives like a nutcase is fun!!
The shop we used to book the tour was PTK travel, for 110k vnd each we booked the group tour ($5 each) which is a good price, I would say the more expensive private tour is probably not needed as they will try to tell you it will be uncomfortable and crowded, but it's really not. I would suggest NOT!! using PTK as they did not deliver on the premise that we'd get to see the sunrise at the sand dunes, it had fully passed by the time we arrived. I don't know what the hold up was, but I got the impression that they really don't care if they deliver or not as nobody will be held accountable for bad service and people will just keep coming anyway. It may be like that for all the tour companies that run this service but I can't really speak for them.
It takes about 15 mins of tough walking to get to the top of the sand dunes, there were other options of quad bikes and a lift in a separate jeep to the summit, these were being offered to me before I even got out of the car. These other options are extortionately priced and the people are pushy. I enjoyed the walk anyway.
