Retrieving input from either GET/POST
I see a few small issues with the code:


Method names: particularly get is quite ambiguous, I'd use something more descriptive like 'get_element_data($element_name)' or something like that. As it is now it is obvious when used but it's not clear when looking just at the class itself.
Instead of  return (!empty($_GET)) ? true : false; you can actually use just return (!empty($_GET))
You don't need to break after return. Some might, however, argue that using it anyway is a good practice that prevents errors. So choose for yourself.


Other than that, I don't see any big problems with it.