The pinch-style lens caps are a really smart and simple innovation by Nikon. These are essentially direct copies, and they are far cheaper than the overpriced (at least in the UK/Irl) spares that Nikon offer.
Upsides:
Cheap! Buy three!
Its threaded, by that I mean it has a piece of thread to attach to some bit of your camera. This is a good idea, and saves drilling and threading your existing lens caps like I have seem some people do. However the thread is not great quality and it will snap if you give it a suitably violent tug (however you're more likely to just pop off the cap, see 'springs' below) or with persistent wear.
Heres the downsides:
Cheaper plastic, so its a bit lighter but also a bit more brittle, so don't expect it to last a lifetime, unlike the Nikon ones which seem to last forever. Also, the weakness of the plastic seems to allow the bit that comes in to contact with the filter thread to wear away enough that it exacerbates problem 2 below.
The internal spring is rubbish, presumably because it uses about 50% of the steel that the Nikon ones do. This means that the slidey bits don't grip the filter threads firmly and there is more chance that the lens cap will pop off if you brush up against something or pull it out of a bag too quickly. So its quite easy to inadvertently lose these things (but this is circular, since you're reading this because you want to replace a lost Nikon cap, right?)
Recommendation: Buy if you're in a habit of losing lens caps, none of the longevity problems above will be yours. If not, get the Nikon ones. Yeah, I know, the Nikon ones are a total rip-off on price, but they will last as long as your lens does.