While I saw an improvement in skin quality, it didn't do much for the scarring. There was some softening of the most recent scar but I don't think it was worth the money I spent.
I still derma roll at home because it has helped slough off old skin cells and has kept my face clear of the occasional pimples I used to get. I use a .2mm and a .5mm. Nothing too intense as I'm using it to refresh the top layer of skin; not the dermis.
Bottom line, it did nothing for my scars. I still think it's worth a try for overall skin health but don't spend tons of money. And I'm not sure if I believe all the marketing tactics re: you need to know how to roll (it's easy) and you run the risk of serious infection (yes, it could happen but not if you keep to the smaller needles and use common sense when it comes to cleaning).