As you can see it is pretty straight forward and easy to use and adds those small photographic imperfections to your image, making it even more photorealistic.
Ok, so what do all these values mean?
Bloom power (value range from 0 to infinity): controls the strength of your bloom effect (the higher the value, the more bloom you get), adding a nice glow to your brighter objects.
Glare power (value range from 0 to infinity): controls the amount of glare in your image, creating those nice star-shaped effects around your highlights, as if you'd be taking a photo with a higher aperture
Threshold (value range from 0 to infinity): this one's a bit hard to explain. Basically by changing the value of this function you change the reach or border of both the bloom and glare effects. The higher the threshold value, the less reach will both of those effects have.
Hue power and hue shift (value range from 0 to 1): these values grant you a limited control of the bloom and glare color. Pretty darn useful for animation and those nice lens flares.
Ray count (value range from 1 to 8): ray count value allows you to change the number of rays in your glare effect. In photography this would be dependant on the number of aperture blades manufactured into your lens. Each ray value produces two "spikes" around your highlight, so the value of 8 will actually show sixteen "spikes" around the brightest part of your image.
Ray angle (values from 0 to infinity degrees, not sure why as anything above 360 degrees is pointless...): this one allows you to change the angle of rays in your glare effect.
Ray blur (values from 0 to 1): this value blurs the boundaries of your light "stars" created by the glare effect.
How does all of this work in real life? I found myself using Glare, Ray count, Ray angle and Ray blur most often, as it already allows you to achieve some amazing effects in your still images, but I'll definitely be using all of these for animation.
Hope you'll find all of this helpful.