Rick and a majority on this forum say Pisa should be skipped or given an hour at most, go snap the pic of someone in your party holding up the tower and you're out of there. Rick calls it "a 45 minute detour form the freeway" (p. 277, Flor & Tusc 2007).
Here's another viewpoint: The Michelin Green Guide for Italy, written by Europeans, give Pisa *** Michelin stars and 5 pages in their Italy book, while giving Rick's darling the Cinque Terre only ** Michelin stars and scarely more than a 1/4 of a page.
Is Pisa worth more than short shrift? Michelin says of the Campo dei Miracoli**: "In and around this famous square are four buildings that form one of the finest architectural complexes in the world, including the Duomo, the Torre Pendente *, the Camposanto *, and the Museo dell'Opera del Duomo." A World Cultural Heritage Center. Pulpits by Paisano.