For 99% of Android device owners, gaming will probably make up a significant part of your daily use. Let's just admit it, for some games, on screen controls just don't cut it. I realized pretty quickly that I needed a dedicated game controller, the only question was which one.
My requirements
Bluetooth
Pretty much a no-brainer. I'm not aware of any wired controllers for Android devices, but it would be somewhat contra-productive to use a non-wireless approach for mobile gaming.
Compact size
I don't want to lug around a piece of equipment three times the size of my phone. A wireless Xbox controller is an awesome piece of kit, but it's not what I would consider a particularly portable piece of kit.
Rechargeable
Some might disagree here. I like the idea of being able to recharge, others might prefer batteries so as not to depend on a usb charger to get their game on.
'Standard' button configuration
A joy pad, 4 action buttons, left and right fire are a must. Additional buttons would be an added nicety.