For starters allow me to explain. I use my nails as tools. I peel things and pry things and poke things with them. I do not treat them well. My job gets them bashed about and I wash my hands very frequently. My nails simply don't grow.
Well, this does what it says--I actually have to clip my nails for the first time I can remember. It's also very very shine and glossy and lasts quite awhile. However: It's very expensive (around 15 bucks..) and the smell is quite strong (read: gagcoughgag!). It definitely has formaldehyde, which is not something I want to inhale regularly. Also, it flakes off and turns an odd colour after a few days.
It's a toss-up...I like it a lot for what it does while it's on and fresh, but is it really worth the price, the smell, the potentially-dangerous ingredients?
It's also a chore. If you use it often and then stop, your nails will likely peel and be in worse condition.
Jury is out on this one. If you like hard, strong nails and don't mind the price or the ingredients and have the discipline to use it regularly, Nail Envy might just be for you!