Flagship Android phones might be getting bigger screens, but that's not making game control much easier. Sometimes, you really need a controller.
There are dedicated phone controllers you could buy, sure, but if you've got a DualShock 3 lying around the house, you may as well use it instead.
Sixaxis Controller turns a PS3 pad into an Android-friendly input device, and while it's a little tricky to get running (and doesn't support every phone), it's still worth looking into, as when it works, it works well.
Sixaxis Controller [Google Play]