The TYLT ENERGI 2K travel charger, on paper, makes sense. It's got prongs that fold out of the body and straight into a wall charger, so there's no mucking about with USB cables and separate charging warts. Just plug the battery into the wall and charge away. We get that. And if you're an iPhone user, that makes sense. Who wants to carry around a microUSB cable that you might well have no other use for?
The reasoning is pretty simple. Three-fourths of the smartphone platforms all use microUSB cables. So do a ton of accessories from game controllers to headsets to pretty much everything else. If you're a multi-device household, or one with accessories, you're good. You've already got them — and their chargers — laying around. It's just not that difficult to dig them out and plug in.
And that brings us to the other reason we'd probably skip this charger: It's a mere 2,200 mAh. And while that'll get you a full charge of an iPhone, it's a little less capacity than what's in the Samsung Galaxy S5, so you won't get a 100 percent charge. For about the same money $40 retail — you can get something about the same physical size, with a far greater charging capacity. (The Samsung external battery I have laying around my bag is 9,000 mAh, and you can easily find other options for even less money online.)
So the question you have to ask yourself is how much do you want to skip carrying around a microUSB cable and charger? If you're on an iPhone, the TYLT ENERGI 2K may make sense. For everyone else, there are better options.