The benefit from playing piano is that it can be used in various different environments, unlike playing an orchestral instrument such as the clarinet or Trumpet; it's not as restrictive and can be adapted in many ways.
It gives you the chance to perform, which is a new skill in itself, you get to meet other people, so there is the social aspect of it, but most importantly it gives you an opportunity to try out various styles of music, and that in itself will improve your musicality.
Rock piano, is fantastic and will focus around Chords, which can also be transferred into playing in a band, classical piano - if you take exams this is how you would normally train, so is the base of your learning but this can be used to maybe accompany singers, or play as a solo pianist.
Blues and Jazz - this will again give you a different style of playing piano, and will improve your performance skills and give you the confidence to improvise and perform solos if you were part of a function band, or in a professional orchestra, so the list of things you can do if you have piano in your life is tremendous.
Playing piano and having any kind of music in your life also gives you a new confidence, most people until they have played a musical instrument or sang have never performed in your life, and to hear people clap and appreciate what you are doing, is a great feeling to have and is a sense of personal achievement, playing piano is very rewarding.