Caught a couple of musical/plays here and the one thing i remember is if you purchase the grand circle seats, be prepared to crane your neck or get annoyed with the ones sitting in the row before you. If they choose to lean forward during the show, it will block your view of the stage. Also, although the seats were fine, they can get quite uncomfortable after a while.
If you have been looking forward to the musical/play, ensure that your ticket is at least for the dress circle seats. Otherwise, the theatre is not too bad.