I have used them & although I am a sculpting girl usually, I have found these very quick & easy to use. But its all personal opinion, they are selling well & now come in natural as well as white. If you go onto Debs board at on MSN - JustNailz, you will see a lot of pics & talk about them on there.
I have just bought some from Karen and find them very quick and easy to use, they are slightly thicker, but i think that helps me to build a nice apex I find them to be ideal for one off wearers, for instance i have quite a few people going to proms this week! of course they can be rebalanced by using your white powder, gel etc. But they are a good time saver!