This reminds me of the woodwork workshop back at school, where you would start filing the edges roughly and then smooth it slowly my using softer sand paper :-P
It works amazing! First I use it to shape my nails then to smooth them step by step. And unlike other flies which leave your nails white of the edges, this gives a really nice look and feel. I use it at least every week and I always have it handy in my bag just in-case my nail breaks during the day.
The Manicare Nail Buffer 4-way is a whole manicure in one tool pretty much.
It has a step by step process which I think is really useful for knowing you really have done your nails in the right order or if you're a manicure novice.
The side I was least fond of was the emery board because I prefer a smaller emery board that can get around the nail a bit more. Other than that I found all the sides really good and they certainly did what they claimed to do. After using this tool my nails looked and felt shiny and revitalised.
If you don't want looks of different nail tools hanging around this is the perfect tool for you.