Someone did test out the right angle head version of the Ultrafire WF-502b that they do, and found that the build quality and finish of the host was significantly better than many cheap sources for the ‘Ultrafire’, although many of these sources actually sell fakes anyway. But the performance wasn’t that great and the UI is of course still very simple and ‘budget’.
I would point out that while the ‘focusability’ of the light sounds good, it doesn’t use optics designed for it. They simply allow the head to unscrew a little and raise the reflector, which takes the LED a little out of optimal focus. This will give quite a messy beam, lose some lumens OTF (they even use a reflector with a flat ring right up to the LED which will cause much more waste, not a reflector designed with this functionality in mind!) and it also won’t spread the beam that much compared to many true TIR/aspheric based focusable lights. But I can see how it could still be useful in certain situations.