I received the power bank last Friday and I took some time to trying it.
First of all I liked the design in shiny white plastic, it seems really solid and well finished. (Looks like a laptop power adapter from Apple).
It worked great with both my Keymaze and GH-561, as well as with an helmet camera and rechargeable MP3 player. However it didn't work with my cell phone, but I'm not surprised, because even to charge it in the PC it needs to install a driver.
It's "inteligent", you don't have to press any buttons or switches, it starts charging automatically, and a blue light blinks meanwhile the charging process, and shuts down some seconds after the cable is disconnected.
Like albert said, it didn't shut down when the charging of the GPS was completed, but I think that's because the GPS keeps drawing some current even when the charging is complete and the power bank only shuts down when there's no drawn current.
In fact, I did some measurements and I noticed that the output current drops by half with the Keymaze when the charging is complete, but it remains the same with GH-561.
I also noticed some problems with NiMH batteries being shorter and sometimes they don't connect, but that's easily solved by lifting a little bit the metal contacts with a screwdriver. (This only happens with cheapo batteries from ebay that are a bit shorter. I have other higher grade NiMH's that are regular size, so the problem are the batteries, not the charger).
Overall, I think it's a great complement not only to the Globalsat GPS's but also to any outdoorsy electronic device that supports charging via USB.
I'll be keeping it on my backpack and I'm sure I will use it during my mountain bike trips.