We're beginning to see more battery pack/cases for the iPhone 5 since Apple has stepped up the licensing for the Lightning connector that is required. The uNu DX is an update to its earlier iPhone 4 and 4S battery packs.
The uNu DX for the iPhone 5 (US$79.99) is a hard plastic case that has a bezel raised above the screen to protect it in a fall. The volume and the mute switches are easy to operate when the case is on, and there is a short pigtail headphone adapter to use since the actual headphone jack is recessed into the case. The charger uses a standard MicroUSB cable, but unlike some competitors like the Mophie battery cases, you can charge AND sync using this arrangement. That is a major advantage, because you don't have to take the case off if you want to sync via a cable. The LED at the rear of the case has different colors to alert you to battery levels: green when fully charged, blue when the battery drops below 70%, and red below 30%. Below 5%, the red LED flashes.
The case is easy to install. It splits into two pieces. You plug your iPhone into the bottom piece, where it engages the Lightning connector. Then the top part of the case easily slides on. I charged the case fully when it arrived. A flashing green LED lets you know it is being charged. When the phone is in the case, the phone charges first, then the case follows.
One thing I did not like is that the battery case needs to be activated with a 3-second press of a button on the back of the case. If you don't, you'll be using your iPhone battery. The mophie system, with a slider that lets you decide if you want to use the iPhone battery or use the battery in the case at the same time, is a bit more intuitive.
The uNu DX has a large capacity battery, 2300mAh. This is larger than many battery cases on the market, such as the mophie iPhone 5 cases. The $79.99 helium case has 1500mAh, and the juice pack air for $99.99 has a 1700mAh battery. I found the uNu lasted about 20% longer than my mophie helium case under similar usage conditions.
I liked the uNu DX case for use with my iPhone 5. I've never had better battery life, and the case seems to offer solid protection at a price equal to other cases that don't offer as much. The uNu has a 1 year warranty and is available direct from the manufacturer and Amazon. The uNu has 'Made for iPhone certification' and many of the inexpensive cases on the market don't, so beware when you are comparison shopping. Mophie and Boostcase are certified as well. The uNu DX comes in black and white.