What are the key features and overall performance of the Roland RP400 as highlighted in a comprehensive review?

The key features of the Roland RP400 highlighted in a comprehensive review include its realistic piano sound, responsive key action, and a wide range of built-in features such as different instrument sounds and recording capabilities. Overall, the RP400 is praised for its high-quality sound and performance that closely mimics that of an acoustic piano, making it a popular choice for both beginners and experienced players.