In terms of physical size and weight, I'd place this at about the same weight as a cell phone and a bit larger than a couple of 9-volt batteries stacked on top of each other. You can easily wrap a hand around it, or slip it into a pocket, and the weight is enough that you'll know it's there. The main thing you should care about with a product like this is how much of a charge you can get from it. My cell phone is the Samsung Epic 4G, and has an extended battery installed. This pack was able to charge it from around 25% to 100% over an hour or so. It did that twice, and charged my brother's Motorola Droid once. Then, it provided maybe 20% of a charge to a 'New iPad' (a.k.a. an iPad 3). For the size, weight, and price, I was pretty impressed. There are two "tricks" to using it. The first is that to initiate a charge from the battery to your device, you need to connect the cable and then press the button on the front of the battery to start the charging. Press the button twice quickly (like a double-click of your computer mouse) and the flashlight turns on (or off). The flashlight is a single, bright white LED and works well enough for basic needs. I haven't measured the time it takes to charge the pack itself. When I've used it, I've just plugged it in and charged it overnight. The charging port takes a standard micro USB cable. For my phone which charges with the same port, that's perfect. It means that all I need to carry is the wall plug and my normal USB charging cable for my phone to use it on the go. (Plus the iPad cable if I plan to use that.) The battery comes with a bunch of other plugs that, honestly, I will likely not use.) The row of blue LEDs on the front provides an indication of the charge left in the battery, or of the state of charging. While charging, the (fairly bright) blue lights will flash to show that it's charging and to indicate the charge level. (This might be annoying in a dark room where you're trying to sleep, but you could easily solve that by turning it upside down or putting something over it to block the light. It's a nice looking product, at least to me. It feels solidly built, and has performed well in three months of ownership.

RAVPower Dynamo-On-the-Go RP-PB03 5600mAh External Battery Pack came with lots of options and a bag that's pretty portable. By just carrying the adapter for my phone, the short cord and the battery around I can actually fit the bag in the same pocket as my phone and even charge my 3vo while walking around. The charge time is great, I can get about 3 full phone charges out of one battery cycle. The 1A output has caused me to look at all my chargers, this is one of my fastest. Very sturdy build and feels like a quality device, the LED is fairly bright and works well in dark areas. If I was a camper, this would be more than ideal. I could camp for days and have a great no worries flashlight, while charging my phone a few times. Operation is easy to learn, my 18 month son learned how to play with the flashlight almost instantly. I have no plans on testing the rated hours the flashlight can work, but with ten days the light can be on, my son isn't going to hurt anything by turning it on.

mAh capacity is good, especially since I can now run my phone (which I put a bigger battery in) for a really long time. I really like that this battery can be charged with a standard micro usb cable. I like the blue charging lights and how they light up when charging to let you know the progress of the charge. I really like that this battery can charge a device and be charged at the same time, something my other external battery can't do. Can't say I have had a need to use the flashlight feature, but I know how it works and glad it is there if I need it. When the wife asks for a flashlight, I'll always know where one is though!