The pianoforte is probably one of the best-loved instruments in the world and has captured the imagination of some of the most talented human minds since it was first invented, in the twelfth century. It's interesting to note that the majority of composers for the instrument have always been its best exponent as performers.
For example, Beethoven wrote a beautiful violin concerto - probably one of the greatest of all time, but he was never a violin virtuoso. Similarly, Mozart wrote for a wide variety of instruments; however both composers were best-known for their keyboard works and were 'masters of the ivories' themselves.
The piano is a good instrument upon which to start learning to play. Like any instrument, its complexity is a function of its player. To wit: It won't take you long to play something like 'chopsticks' but you'll have to stick with it for a few years until you allow it to become an extension of your mind and body and to play Rachmaninoff's third piano concerto! Rachmaninoff is indeed one of the world's most revered composers for the piano, and he was also a maestro at playing it. It's quite amazing that there are actually recordings of Rachmaninoff playing his own works. His compositions have been the subject of so much interpretation by other pianists that his original recordings sound quite 'mathematical' in their delivery.
Interpretation is probably most profoundly evident in the piano works of Chopin. There's probably no music at all that's marked up with as much 'rubato' than that of Chopin - the composer who is renowned for changing a key in a flurry of trills, scales and arpeggios that are virtually impossible to follow if you are witnessing hands at a keyboard. Chopin is widely regarded as the 'poet of the piano'.