Effective, I think...?
589053
Well, I don't know how I feel about Nail Envy. First, I think it works better than any other nail strengthener I've used. It makes your nails look nice after it's applied but needing to reapply it every other day is a pain and creates a very thick layer of polish, so it will likely peel off by the time the week is over (when you'd need to take it off anyway). It may have been a weird placebo effect, but I do think it strengthened my nails. I had PAPER THIN nails that had taken a lifetime of biting and clipping, so they bent extremely easily. This made growing them out nearly impossible. Nail Envy allowed me to get past the point of no return, where I had never gotten before, but I can't credit my new nail strength to Nail Envy, alone. I also started taking 5000mcg of Biotin daily ("the hair and nail vitamin) and THAT is what really improved my nails.

Overall, I definitely recommend Nail Envy to people who need help getting the process started. I didn't experience any weird side effects like peeling, the way other users have. It's at least half the cost on Amazon compared to retail, so try it.
3892394
Hard to tell if this works.  i think it does, but not super evident.
1362849
I noticed an improvement right away, after a few days, but not sure if it has wore off or just not as effective as I originally thought.  have to rate a 3 start right now and will come back in a month or so after being on the product longer.
491093
So far, I think it's serving its purpose,  as I can't see it working. I assume it's working. I'm not sneezing and coughing as b/4.
2850835
I'm not at all convinced that the relatively small amount of product in this filter (looks like a cup or two of charcoal pellets at best?) is very effective at all, much less for the advertised filter life, but I'm not able to back that up with anything more concrete than my nose.

Instead of dropping another 30 bucks on one of these I'll be investigating DIY solutions such as the cut-to-fit charcoal media one can find right here on Amazon.
709848
this is a special kind of drama to put up, bu where it works, it looks good and is effective. I recommend having helping hands.
update:
watch out for it bubbling up after a while.
2323507
Sometimes is seems to work, other times I wonder if it's doing anything at all.
3920642
Fairly easy to put on. Can't really tell that it is there which I seem to think is the point of good protection. Whoa! Did I just say that? ;-)
247394
Seems like it will do what I want it to do.  Haven't had enough time with it, but it's promising.
1921458
I have not used it enough yet to make a detailed comment.  It seems, upon perusal, that it will be useful.
3211309
Haven't read it completely, but what I have read seemed helpful.
2099200
Great product. Nice and effective product, good enough!
2379694
Im not sure how you would rate this! I guess it works.... I watched a YouTube that said it doesn't make a difference! So; who knows?
3515040
I have utilized these about 3 times already and have found them effective.  However, I am wondering if they will be long-lasting.  There is more plastic than I anticipated and this device has to stand up to pressure.  We'll see.
2020408
I gave it as a gift, so I can't rate it precisely.
But no complaints from the recipient, they seem to think it works fine.
148044
Perfect for it's intended purpose, and I'll probably think of other ways to use it too!
494115
I really think this does work. It could be psycho-somatic, but I can testify to at least feeling that this was not a bad purchase....