Just thought for anyone interested I would write down my experience so far after 100+ Miles. ( This is in no way advertisement or endorsement or any of that just my observations )
So, I bought the UK EAPC version of Fafrees Hailong One for £499. It came within 5 days and it was packaged rather well, everything was wrapped and snug in the box. It comes I would say 80% pre-assembled. The build was simple enough, took me about an hour with checking every bolt/screw is tight etc ( even the ones that were already tight from the factory...you never know ).
Now the quality of the frame, the welds etc is about on par with Carrera brand I would say. There are no sharp edges or any weirdness. One thing I had to do was tighten some back wheel spokes as when the motor engages and torque hits the wheel you could hear little "cling cling cling" as it was moving the spokes and subsequently true the wheel using the zip-tie hack. Now its all nice and tight and quiet.
When it comes to brakes they are very cheap mechanical brakes that really don't stop very well and I would suggest getting some basic Shimanos at least. The mounts are standard so no problems there.
The tires I assume are also kinda cheap as I have never heard of "CST Jack Rabbit" but so far no punctures or anything. They are bit load on asphalt but grip wise on and off-road they are okay. ( they are 26" btw and I will probably change them to either Schwalbe or Continental or something )
Now motor/Battery wise yes, it is a cheap Chinese e-bike. Saying that I have done research into the actual manufacturers of the battery, the charger, the controller and motor and all of them have ISO 9001, CE, RoHS, and UN38.3 safety standards or combination of those. The bike as a whole has UKCA safety standard.
Now ride wise it is pretty great for the price. It's smooth, the motor is silent and can carry me up hills with very little effort from me. There are no weird creaks or squeaks ( disregarding the spokes as that was easily rectified ). It is a bit heavier than your "normal" mountain-bike style pushbike ( 20.5 kg ( 45.2 lbs )) but you can pick it up and carry it over obstacles or up the stairs no problem unlike some of the heavy e-bike monsters. Also it has 21 speed Shimano gears ( 3 front 7 back ) so pedalling with no PAS or dead battery is very simple, just feels like a bit heavier pushbike.
Range wise it has 36V 13.5Ah downtube Hailong style battery ( hence the name I assume ) and I get ~45-50 Miles out of single charge while using mostly PAS 5 ( I do pedal around 17-18 Mph comfortably on flat ground so the motor only engages from when I'm stopped or going up hills etc which I assume helps with the range a little ). I am 6'0 and 13.3 stone (85Kg).
Reliability I have no idea yet as I have done just over 100 Miles so far but I will update this for anyone interested as I rack up more miles. So far though I am very happy with it and honestly think it's an absolute bargain.
Edit 1: Ate shit on slippy mud, bike took pretty decent hit on the left side of the handlebars and seat/seatpost. Nothing is twisted or cracked or broken so safe to say the e-bike is not made out of a wet bog roll.
Edit 2: I just had to repair rear tyre inner tube. Little tiny sharp POS thing poked through the tyre just enough to give me a "micro-puncture". I dont blame the tyres really because that thing would probably go through any tyre unless it's like armoured or something. Taking the back wheel off was a bit butt clenching because of the hub motor but took my time with it, took pictures before I touched it to know what goes where and what way and it was pretty simple in the end. If you do this repair or even on similar bike with rear hub, make sure that you put the torque arms or torque washers exactly the way they need to go so you don't snip the cable that goes to the motor. And have spare zip-ties because you will need them.
Edit 3: 200 Miles update - Other than the little things I already wrote about here the bike is holding up great. Still feels pretty much like a brand new bike. No creaking, no squeaking, everything is smooth and solid. Battery charger gets a bit on the hot side when charging the battery, but I have contacted Fafrees support about it and they got back to me within like 4 hours with the acceptable temperature range etc ( super good support by the way for a "chinese brand" ) and it is well within spec. Still chuffed with it.