One advantage of a Bluetooth controller like the Duo Gamer, theoretically, is that you can use it while you're on a couch and your iPad's connected to a large-screen TV. That's true, but for how many games can you enjoy that rare experience? I count five, (actually fewer considering one didn't even work). Discovery Bay is clearly selling that element of the Duo Gamer, but the Duo Gamer has to be a more versatile controller to be of use that way. With the current handful of games, it reminds me more of those TV plug-and-play Jakks Pacific controllers that came bundled with old Sega Genesis games. Only, in this case, there are no bundled games. You have to buy those separately -- at anywhere from 99 cents to $6.99 a pop.
The tiny Duo Gamer can slide into a backpack, but it's still over twice the size of an iPhone 5. It won't fit in your pocket unless you're wearing cargo pants. It's ugly but functional. It wouldn't even pass as a B-level knockoff controller at GameStop.
The Duo Gamer comes with a stand, which fits the iPad 2 and third-gen iPad well and accommodates the control pad. Bluetooth pairing happens simply enough with the press of a button. It comes with two AA batteries. That's all I can say positively about the Duo Gamer. I wish there were a universal iPad controller, but that day isn't here yet. I don't know when that day will even come.
If you want a fun retro game controller that works with a good handful of games, get an iCade. If you want a handheld game system with buttons, get a Nintendo 3DS or PlayStation Vita. If you want to play games on an iPad or iPhone, use the touch screen. The Duo Gamer just isn't what you and I were looking for.