I've used them and did find the application fairly easy but, although they said that the natural nail grows underneath them with no problem, I found when I eventually removed them that the surface of my natural nail was anything but perfect and my nails seemed weak and brittle.........in fact they were worse than they were before I used the acrylics.
So I started using OPI matte varnish, on a friend's recommendation, and now my nails are really long, they're no longer brittle or marked etc and they're very strong. In fact, people now ask me if they're false.
So personally, I'm steering away from any form of acrylic nails.