We saw this waterfall from the Vietnam Side (Ban Gioc Waterfall)as we did not have visas to enter China.
The view from Vietnam is very different, as you can only see the Ban Gioc Falls. We were there in October, and the river was quite full. Visitors can take flat boats from either the Vietnam or the China side to get closer to the falls.
From Vietnam the easiest way to get there is through Cao Bang, but it is a hard journey on difficult roads for about 5 hours. It was well worth it to see the falls though.