The graphics are brilliant for a mobile game. They've been improved from the console version, to graphics similar to the PC version. Nothing has been scaled down or held back for this version.
The controls are all touched based buttons on the screen. There's a button to get in to a car, a button to sprint etc. They all work really well and are all really responsive for the simple actions, but it gets awkward and starts to fall apart when actions such as drive-by shooting are performed.
I'm sure the majority of people played this back in the day (personally, this is my favourite GTA game), but I'm sure it will be a blast for everyone to play this on a mobile device. It's not so much suited for quick play sessions like most mobile games, as to save the game you have to drive to a safe house, but it's certainly a different type of game to play on mobile.
I think it's better suited to larger screens like tablets, but large mobile phone screens can handle it easily and it's not too cramped with the virtual buttons on screen.
The app is about 9MB to download off Google Play, but a further ~500MB needs to be downloaded before playing through the app itself. Android phones that support it can also have joypads connected to the device to play with one of them, too.