Desire Design's More Pro Pod Kit has an internal battery with a capacity of 1,000mAh. Given its overall size, that is pretty impressive. In addition, the micro USB charging port is on the side rather than the bottom, so you'll be able to charge the device while it's upright.
Not to mention, it does feature a chipset by Desire, providing you with various safety features, which is always a good thing! Also, it does have a single firing button, so it's very easy to use.