I've only used the mask a few times, but it was the only one on the filed that did not fog up those times. It is very comfortable and is easily adjustable. It is also offers excellent ventilation so it is easy to breathe through.
Not, much...Once in a while the elastic strap in the back comes loose and needs retightening. It could use a little more throat protection, but that isn't really a must.
This mask is an excellent value for anyone but someone who needs the finest of the finest of quality. It should do for anyone else. The field of vision is good, it doesn't fog up unless you run for extended periods of time and then stop, and it is very comfortable. A good purchase.