I carry a SC64w HI regularly and it's my "best" all around light.
Some of the good points:
Amazing output to size ratio
Good quality
Good interface with quick access to lots of different brightness levels (especially after programming)
Good mix of throw and flood
Lots of option from very dim moonlight mode to very bright light up a good sized yard
It's an efficient light
Downsides:
Price - you can get a decent flashlight for less (convoy, etc) but I would argue that it's lower overall quality.
Quality - you can get a more reliable light (malkoff, etc) but you will pay significantly more and they will have less output for the same size.
Not a great choice for defensive carry (with a gun) because it doesn't have a rear switch.