For one of your first application/games with C++ and SFML, your code is extremely good!
Clean interfaces and nicely organized code, if only everyone would start off that way...
Here are a few suggestions, how you can make your code even so slightly better:
- Use SFML 2 - see here for more information.
- Pack your code from main.cpp also into a class, e.g. Application or Game, and only create an instance of the new class in the main function. (Similar on how'd go about in Java, just with main part outside of any class.)
- The one-line if statement bodies in Paddle::input could need some indentation, so the flow gets clearer.
Other than that I can't really critics more, then again the codebase is rather small so eventual design issues, might only become clear in the future.
