It doesn't feel necessary.
Maybe I just have fairly smooth nails to begin with, but I just don't feel like this does much for me. I don't feel like it smooths out my nails much more than an additional coat of polish would and I don't feel like it makes my polish last longer or stain my nails less. One thing I have found it's good for is making lighter polishes go on more opaque since it sort of makes the white ends of your nails stand out less under sheer polishes.
I LOVE this product!!!
I don't know about you, but I've gotten nail enhancements for years, which can take a long term toll on your natural nail and so once a year I have my gel nails removed completely so that my natural nails can heal. However, they usually look like crap in the process; so I cover them with nail polish. But the polish on my weak nails always looks like it was done by a kindergartner because of the lumps and bumps on my nails ... NOT WITH THIS PRODUCT!!! I put this on before my polish and not only does it smooth everything out, but it conditions and provides an awesome base!!!
OPI's Ridge Filler! Where should I begin with this amazing product? Well first I should describe my nails. Before I got this product I would always notice tiny lines and dents when I painted my nails. I have very weak nails so if I layer on the coats of nail polish there is more of a chance of the paint chipping within a day or less. So when I first heard about a Ridge Filler abut two years ago I just HAD to put it on my birthday list. And that loved bottle I got for my 19th birthday has been the same one I use with EVERY SINGLE manicure for over a year and a half. I had to thin it out once a few months ago, but other than that I don't have any downsides. I apply this after OPI's Natural Nail Base Coat and before any nail lacquer. I used to apply it as a base coat, and I haven't seen any difference between using a real base coat first or using the ridge filler as a base coat. It smooths out all my lines and ridges and I really notice when I don't use it. It doesn't have any strong smell, and if you ask me, it has less of a scent than all my other polishes. Although I haven't tried any other ridge fillers, I would highly recommend this one. Unless of course you were born with perfectly smooth nails! Haha, don't we wish?
Overall: 5 out of 5 stars and two thumbs up!