Power is provided by built-in battery, but also via USB connection cable. With USB bus power the lamp always has the maximum brightness and is slightly lighter. Lights all 4 LEDs, it is one of the brightest USB-powered LED lights that I know. A laptop keyboard is lit bright and very readable.
Through the clip you can attach the lamp, for example on notebook cover or use it as a work light. Combined for example with a commercially available USB Power Bank you can run a flexible lamp over many hours or days so for various applications (camping, workshop, etc).
These are the goosenecks fragile I would not say. I have not yet back-and-forth bent this all day, but I know of similar lights already, that this type of flexible metal hoses will eventually tired material. But this I can not find anything so far.
The USB circular connector is not widespread, but this will indeed supplied as an accessory. For the price you can not go wrong in my opinion.