I've had LVL a few times and really like it. I did have one bad experience where my eyelashes were frazzled afterwards - totally crimped and fried, awful-looking - and I had to wait until they fell out and regrew over a couple of months, but that's once out of maybe five times.
LVL doesn't increase the thickness or fullness of your lashes - just darkens and curls what's already there, so it's a lot more natural-looking.