What are the long term effects of Fraxel Lasers?

I've read horror stories avout Fraxel where the individual had good results initially, but within a couple of years they had holes & uneven lumpy skin post treatment. The pictures are difficult to look at & concerning, especially since i recently tried the Tria age defying device. Were these problematic results due to practitioner error/incorrect use of the type of lasers or are the long term effects of lasers still unknown? Or is it because certain individuals are not good candidates for lasers?