I haven't timed it, but it seems about the same as using the regular charger plugged in to the wall.
My official Apple wall charger has a 1 amp output, and this thing has a 2.4 amp output, so in theory, it should be faster than plugging in to the wall, but the phone probably has some circuitry to drop that back down to 1 amp.
There are other products out there that do the same thing for a little less money, but I wanted this for a weekend camping trip and Target had a bunch of them on the shelf. I didn't want to pay for express shipping ordering something else online. (Like one of the the
Anker 6000 devices, which also look nice.)