I really love this product, and have been using it off-and-on for a couple years. I have really thin and weak nails, and when not properly taken care of, they snap off, break, and peel/chip. They get really dry (as do my hair and skin). I hated that I always had to keep them short.
At one point, i found Sally Hansen serum, at my local grocery store for about $8. It was a little pricier than I liked, but decided to give it a try. Originally, I had used the serum with the nailgrowth miracle polish that is supposed to go with the serum. I did not like the polish, as it peeled easily and actually caused further drying to my nails (so eventually I just started using a regular clear top coat polish, just to seal my nails and protect them). I used the serum every morning and every night, and definitely saw a difference. After 1 month of continuous use, my nails were not only longer, but also stronger. I've dinged them several times over the last month, and normally they should have snapped off- but not even a crack. :) I don't really have problems with my cuticles (I barely have any), so I can't say if it moisturizes cuticles. But it's certainly helped my nails. :) I think it's worth the money.
The thing is that you need to be consistent with it- use it everyday (at least before bedtime), and in my case, always keep a clear coat on your nails while they're growing so they won't peel or flake as they grow out (which is what happens to mine if they're bare for too long and exposed to the elements).
As some people have said, the key to making the dropper work is you have to squeeze the little white cap before putting it in the bottle, so it can suck up the product into the dropper. The one thing I dislike about the product (but it's not a deal breaker for me) is that bottle being opaque. While it makes the bottle look pretty, I don't like that I can't see when I'm running low. I only know to buy more when the dropper has nothing left to suck up, lol. Overall, I think the product is worth a try. It does take times and some work, but it did make a difference in my nails, and I use this stuff when I want to have long nails :)
*Also, a little bit goes a long way. Just a tiny drop per nail. This product lasts me a long time before I need to purchase more.