According to the commercial, it's "The battery operated light bulb that you can install without an electrician. Just stick up the base, slide in the bulb, and you've got light. It's that easy."
The information on the Instabulb box makes a big deal about "no outlet or wiring needed" but the box fails to mention that batteries are not included. You need 4 alkaline AA batteries in order to see the light.
For our test I took the Instabulb to an underground parking garage. First stop, the dark, mechanical confines under the hood of an SUV. The Instabulb does shed more light on those difficult to see engine components. The recessed dip stick comes out of the shadows. The bulb doesn't give the "brightest" illumination, but all-in-all it's not bad.
Next stop: A dark garage storage unit. Here, I have to peel the paper off the back of the base to expose the square of adhesive and attach the base to the top of the shelf. The bulb unit slides into the base. I pull the cord, and, again - more light and much better visibility.
Finally time to check out one last advertising claim: "Unlike glass bulbs that break, the Instabulb is shatter proof if you drop it."
The commercial says the bulb won't shatter, so I unscrew the bulb from the rest of the unit and drop it multiple times to the cement floor. It doesn't break.
So Instabulb gets a thumbs up, with this word of caution: If you attach the base using the stick on adhesive, good luck un-sticking that base from your wall or shelf.
On a scale of 1 to 4 I give it 3 stars. Instabulb performs well in small spaces where more light is needed, but I found the actual light source to be on the dim side for lighting larger spaces such as a big closet.