Pros - portable, battery powered, the amp and battery fits into standard backpack ...ideal for camping, festivals, busking, etc. when you are accompanying acoustic instruments...wouldn't take this on tour, naturally, but great in a low-volume setting. Also has iPod aux in, which is a nice touch.
Cons - its not going to replace your regular amp
I also own a Double Four and use it for off-grid applications, like camping, bluegrass festivals, and busking. I've used it primarily with an NS design upright stick bass (NS-CRM) for bluegrass, but also have used it with conventional electric bass camping, as well as a small PA when hooked up to my iPod. Good sound. Not going to level any small buildings or replace your regular amp, but ideal for what I was using it for. Echo what the other reviewer said about the laptop battery being an ideal power source. The Double Four, Battery, and chords all fit within a standard-sized student backpack, that I carried it on a Southwest Flight with no problems and no questions asked.
If you are looking for a high quality portable bass amp that can be used outdoors with a battery, this is it. Nice,accurate and tight sound. It requires 20vdc so you will have to buy a battery like a Lenmar PPU916rs,otherwise,it comes with an AC adapter. Until another amp comes out with the battery included in the unit, this is the Jones!