The touchscreen is more than enough for mobile gaming if all you play is Candy Crush Saga or similar casual games. When you start playing games with complex controls, a good controller helps a lot. Controllers are obviously not going to fit in your pocket but having dedicated physical buttons for all your controls is a big plus. You'll also appreciate the controller if your phone tends to heat up when you're playing games, as you won't have to directly hold the device.
If you're looking for a controller for your phone, your choices include the Amkette Evo Gamepad Pro 2, the Mad Catz C.T.R.L.i, and the slightly cheaper GameSir G3. We used the G3 for two weeks with a variety of games. Here's what you need to know if you're thinking about buying it.
Design
The GameSir G3's outer shell is made of smooth plastic that has a slightly slippery surface that makes it hard to grip sometimes. Its two analogue sticks have a rubberised coating and it has four rubber buttons - Start, Select, Turbo, and Clear. The analogue sticks were easy to grip and gave us no trouble but we found it hard to use the other rubber buttons. Those four buttons felt too small and the Start button in particular is a bit too close to the X button.
Other than that, all buttons are made of plastic. This includes the four-axis D-pad, four buttons (A, B, X, Y), a G button (home), two shoulder buttons and two trigger buttons. The trigger buttons curve outwards, which is great if you play shooting games, but we felt they should have been a bit longer for better grip. Our fingers slipped off the trigger a few times.
Performance
The base of the controller has pairing instructions for Android and iPhone. Pairing with an Androidphone is very easy, it works just like connecting any other accessory via Bluetooth. The GameSir G3 doesn't have Apple's MFi (made for iPhone) certification, so we wouldn't recommend it for use with iPhone. We managed to pair with an iPhone 5s via Bluetooth, but the controller didn't work with games such as Leo's Fortune, which supports MFi controllers.
See more at: http://gadgets.ndtv.com/games/reviews/gamesir-g3-review-affordable-controller-for-android-games-851294