This Jet Black iPhone 7 scratch test shows what regular use can do to Apple's new glossy surface27
Performed by Cnet, the test confirms what Apple itself said when it unveiled the jet black iPhone: the "high shine" of the handset "may show fine micro-abrasions with use." For the sake of comparison, the jet black iPhone 7 is pitted against a silver iPhone 6s Plus - which, while it's obviously not scratch-proof, fares much better than the newer device.
It seems that the glossy surface of the jet black iPhone 7 will easily suffer damage from everyday use (unless you protect it with a case, or you don't really plan to use the phone that much). If you do want a dark iPhone 7, perhaps you should consider getting the mate black model, since this isn't as scratch-prone as the jet black version.