Lembongan is beautiful, get a local to show you the sights...I travelled with a 16 year old and 9 year old.
The wifi was shocking, especially for teenagers on social networking, but I believe that is across the island and not just at the cliff villas. The cliff villas were as described but take word the stairs are steep and many....again something the kids were not impressed at, the paths are dangerous but again this is island wide. Bring lots of bug spray as mosquitoes are everywhere, especially as cliff villas are in the forest.
I would definitely go back to Lembongan but would stay at dream beach resort, more people and interaction. If you are looking for a hideaway with a book from the real world cliff villas is perfect.