I know a few who've had them.  No problems and they liked them, BUT very $$$, frequent maint (also $$), and very time consuming to apply.  Facial cleansing and showering kinda a PITA so as not to compromise the glue (make sure it does not contain formaldehyde).  Definitely make sure the person is certified (aesthetician).  I might consider it for a beach vacation - maybe - but $350+ & 2+ hours for something that's only going to last 3-4 weeks - doubt it.  I use Latisse 2Xweek.  Not the same thing, but with Lash Stiletto or Blink mascara, I often get asked if I have extensions.