I have the zumbrella version of this marketed by David Ziser (only it costs twice as much and doesn't include the cover) and it has served me well for two years as I have hauled it around the world in my backpack with a few speed lights and a Justin Clamp. The compact folding size makes it ideal for anyone with space concerns, but it also means that it extends larger than the other umbrellas available, creating a larger light source, and thus a softer light source.
This tool also produces very attractive catchlights in the eyes of subjects, and can be used not only as a shoot through umbrella, but also as a diffuser that produces a convex light that is more sculpt able than a flat diffuser. By the way, shooting light through this umbrella is the only way to go--it double the power of your light and allows for a softer quality of light without the specular highlights create by the silver reflective cover. Place your speedlight at the end of the stick (as far from the fabric as possible) to fill the umbrella with light instead of just having a small hot spot shine through and move the fabric as close to your subject as possible, and Bob's your uncle, you've got amazing portrait light. Or still life light. In fact, try just opening the umbrella over a wildflower in a sunny field and amaze your friends with images produced by your ultra portable light tent. Spray it with silicone water proofing and extend your shooting conditions to include Spring in the Northwest.
This umbrella really is that great. I just bought two more because after two years one of the spokes was stepped on and is *almost* broken.