If you haven't seen the show, go and do it. If you have, well done.
What many piano arrangements for recent Broadway musicals nowadays such as Wicked, Mamma Mia, and Spamalot have in their respective arrangements is a lack of a challenging score to play, though it may sound easy, and how oftentimes, they composer tries to alter the original score into something more adaptive for the public. Although this may sound like a good idea, it really isn't, because as soon as you play it based on the arrangement or sing it, you quickly realize it's not as good as the original, which is what everyone wants, right?
The Avenue Q Piano arrangement, however, keeps all the songs in their original context, letting everyone emulate the classic songs the way they're supposed to be sang. No one wants to sing "Defying Gravity" from Wicked without the chorus back-up or Glinda singing in every now and then, right? Avenue Q gives you the score straight from the source, without awkwardly messing up the original greatness of the music. A must-buy.