As many have stated, it fits the keyboard just fine. Since it does not use any adhesives, it just sits on top of the keyboard. This is both a good thing (easy to take off, clean, put back on) and bad thing (slides off if you put any force while typing or holding keys, like while playing games).
The problem is that at least for both me and my wife, we both feel that it makes it very slightly harder to type when I installed it on my MacBook Pro 15 Retina. Most keys have around 0.5mm of blank space between the protection film and the key itself (it's very loose-fitting), so the tactile feel and response becomes duller. As a consequence, I end up typing slower, even after a full day's use. Sometimes, light keystrokes did not register at all, and had to tap a second time. I suppose if you typically use sufficient force while typing, this isn't an issue.
The other problem is that it adds an extra 0.5-1.0mm of thickness to the keyboard, so the cover will come into contact with the screen a lot. This could potentially mean transferring a lot more finger oils and dust to the screen, and I've opened my MacBook with the cover stuck to the screen once already.
Overall, this could still potentially be a useful product for added protection and cleanliness of your MacBook keyboard, but it comes at a rather high cost. Perhaps a better brand exists that fits slightly better for better performance and feel, so you may wish to look elsewhere.