For reference, here are the battery capacities of some of Apple's recent devices:
- iPhone 4S: 1,420mAh
- New iPad (third-generation): 11,560mAh
- iPad 2: 6,930mAh
- iPad 1: 6,614mAh
Looking at these numbers, you can see that the Peak 6000 will fully charge the iPhone 4S and many other smartphones more than three times. And, as I said, you can charge multiple devices at one time, though that will obviously suck the life out of the Peak 6000 more quickly.
HoMedics, the company behind MyCharge, also sells an earlier version of this product, the RFAM-0007 Portable Power Bank 6000. That model costs less (around $60 online) and doesn't feature the built-in wall-socket charging capability. Also, the newer Peak 6000 integrated connector design is better, though the Power Bank 6000 has an added Mini-USB connector.
In all, I really liked the Peak 6000 and appreciated its versatility. That said, if you're thinking of getting the iPhone 5 or whatever Apple turns out to call its next-gen iPhone, you may want to wait before buying this because if Apple shifts to a smaller connector, the integrated Apple connector will lose some of its appeal. Apple will most likely offer an adapter you can use with its larger connector, but then you'd have to carry the adapter around with you. Or you could just get a more standard battery brick that doesn't have all the built-in connectors. Monoprice sells a no-frills 5,000mAh battery for around $30. At the higher end, you can also pick up the ruggedized Mophie Juice Pack Powerstation Pro 6,000mAh. It retails for $130 but is dustproof and water-resistant.
Interestingly, when the MyCharge Peak 6000 first hit the market, I saw it selling for $65 online, which would make it a bargain. But it received some favorable reviews and the price jumped up to its list price of $99.99 (at the time of this writing, it seemed to be out of stock at Amazon). At that price, it's not a great deal, though it's also not grossly overpriced -- especially considering its versatility.