Wireless charging on the latest iPhone is convenient, but it hasn't been very fast. Apple's iPhone X, iPhone 8 and 8 Plus are about to get a little bit quicker about it, though, with the release of iOS 11.2.
MacRumors' testing suggested a slightly faster charge. On a Belkin charger that supports 7.5W speeds, the iPhone X went from 46 to 66 percent charge in half an hour, as opposed from 46 to 60 percent on a 5W charger. That's slightly faster.
The current Qi standard, version 1.2, allows for up to 15W, so Apple isn't in the lead here. Still, 7.5W is faster than what you can get right now, so if you're buying your first Qi charging pad, check the box to make sure it outputs at least that much of a charge.
iOS 11.2 is in public beta right now, and usually a full release isn't far behind. Expect it in the next couple of weeks.