Not bad, but as CGillusion said, add a bump map for the floor. it looks very unrealistic and flat.
you should also scale it down a bit it's pixely and kind of stretched. you can also see that it's tiled.
I'm guessing you are using a daylight or sun system in combination with mental ray? try uppen the diffuse bounces so the red ball actually casts some red on the floor and same for the others.
There's also a tricky part, the chrome and reflective materials should be casting caustics, it's a hard part but once you got it right it will look even more realistic.
last thing on my side is, it's too clean, most clean renders don't really look realistic, some of them do, but not all. try and add some minor scratches and/or dust/dirt. it will look alot better.
keep practising you'll get better fast :)