Remote Mouse is an application that turns your iOS device into a remote mouse. There are two apps that you need to install to get this suite to work. The first one is installed on your Mac. Think of it as the server app. The client is then installed on your iOS device (iPhone, iPad, etc.). When the two applications are connected to the same wireless network, they can see each other and you will be able to use the iOS device to control your Mac.
On the iPhone side, you will see that there are both a virtual keyboard and a trackpad. So, you can use the trackpad to move the mouse pointer on your Mac and also click with the left or right buttons, and when you need to input text, you can call the keyboard. The iOS app works in portrait and landscape mode. If you use it in landscape mode, the keyboard will have more buttons, including arrow keys and function keys, but there won't be a trackpad.
In my testing, the iOS app was responsive and the pointer of the mouse moved fast and sensitive enough for me. I didn't have any problems trying to get both apps to connect. I simply used the "Auto connect" feature.