It looks like a really good kit for the money.
It doesn't say the speed of the motor, which is an important characteristic.
15 amps would normally be called 250w rather than 350w, so don't expect more power than any other 250w kit. It's a shame that the controller isn't 18 amps, which is what I'd have preferred.
It says throttle up to 6 km/h, but it's almost certain that you can change it to full-range in the LCD advanced settings. You'll also be able to set the speed to the motor's maximum - probably about 23 mph, but could be anything from 15 mph upwards.
Pretty good that they supply all the tools too.
The only thing to look out for is that the motor's spoke flanges are off-set from the centre. Often they still build the rim symmetrical to the spoke flanges, so, if you have rim brakes, you have to adjust the spokes to get the rim central in the frame. I'm not saying that it is like that. You won't know until it arrives.
Finally, cassette motors are not as waterproof as freewheel ones. Water can get in at the back of the cassette spline, so be careful on salty wet winter roads. If you pack in a load of grease around there, it helps. No problem if you don't ride when it's wet.
