I bought this for my galaxy s3 as I missed the gamepad on the Xperia play. However, the problem I have with it is the sheer lack of supported games. I believe there is a list of about 40 games which are supported on their website.
Having said this for emulators, I get the feeling that it is designed for this, it worked very well. Once you have connected it via bluetooth which worked straight away, then map the buttons in the emulator, the Gametel worked like my previous Xperia play. The clip was strong and just fit my Galaxy S3 in and the d-pad, buttons and shoulder buttons felt good.
Overall it is a well made product and is excellent for emulators, but it is let down by its lack of supported games and it is by no means a replacement for something like the Xperia Play.