I've heard they last about 2 weeks. I know several people that have and love them. I've been on the fence b/c they are so expensive to get and maintain and so time consuming to get applied. So I'm not sure I'd do them. Maybe for only a special occasion or vacation but not just for everyday life.
I've also heard reviews that they eventually thin your lashes over time. Which is a risk I'm too chicken to take
I had them for my wedding and I had them for a few months before to test out different ladies and see who i liked the best. It is really important to get someone skilled at doing it. I have naturally long lashes so i didn't get much more length but just fullness. It looked awesome. I could go out of the house with barely any makeup and look great!
It was great for the honeymoon! I didn't notice any thinning. Although I thought my lashes looked all thin but it was because I had the extensions and then they slowly came off.
Depending on how many are applied and how gentle you are they can last up to a month. The last set I got lasted about a month. For me I will only do for vacation or special occasions because laying there for two hours is just too time consuming to do it regularly. even though the fills are about half the time but still. Not to mention they aren't cheap.