"Does what it says."4.0 starson by Jon
Pros: I like the smallness. Easy to carry in my "man bag", or my pocket without a problem. Well built and adds 2x the battery life when needed. Charges easily with the included plug and synch cable. Good for what I need. Charges when in use as well.
Cons: It's a bit awkward to use the phone when this device is added, but it's doable.
Summary: If you need extra power on the go, this is a very small, convenient device and works exactly like I expected. I've used it now for almost a year without difficulty. Bought originally for my original 1st generation iPhone, then used it with my 3G when we upgraded, and now with my new 3Gs. Works equally well with all three.