From David Gilson's review:
I tested the Turbo Charger 7000 with my Lumia 800 (1430mAh) and my Nexus 7 tablet (4350mAh) during a weekend away. The aim was to get through two days without taking power from the mains. Keep reading to find out whether that was successful or not!
I am impressed with the Proporta Turbo Charger 7000. So much so, it’s now part of my essential tech kit whenever I go away for more than a day. For example, if I were staying away for a single night to cover a tech event, I feel that the Turbo Charger would enable me to take my tablet and a Bluetooth keyboard instead of my laptop, without a mains adapter. Similarly, if you’re going away for a few days and only need to keep your phone powered, again, the Turbo Charger 7000 will be an excellent device.
The Turbo Charger 7000 also would be invaluable in the home, if kept fully charged it would keep you connected during a prolonged power cut. I would even suggest keeping one in the glove box of your car – it could be a real life saver.
Pretty much summing up my own feelings on this accessory - here's my own AAS review of the Turbocharger 7000.