Solar Battery Chargers

I see these things available locally for around $40 bucks. They claim to be
able to recharge cell phones and laptops. They also say they're good for
trickle-charging vehicle batteries.

My thinking is that a solar charger would be great for Sun N Fun and
Oshkosh -- places where my cell phone (and walkie-talkies, and laptop)
batteries routinely die after a few days. It also looks like something I
could use to keep my motorcycle battery charged over the winter.

Anyone purchase one of these? Do they work as advertised? How long does
it take to charge? Do they require direct sunlight?

Thanks in advance!
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"