By way of comparison, the Uffizi Gallery in Florence is a bit like the Louvre in Paris: a huge, fascinating museum packed with some of the most famous works in the history of art, which always attracts a huge crowd.
Leonardo da Vinci, Michelangelo, Botticelli, Uccelli, Giotto, Raphael, Titian, Caravaggio, etc, etc... great names and a succession of masterpieces will make any painting lover's head spin. Even if you're not a specialist in Renaissance painting, some of the rooms in the Uffizi Gallery will seem strangely familiar, given the fame of the artists and their canvases.
In other words, a visit to the Uffizi Gallery is a must in Florence! It's not a visit you can improvise, however: one of the most famous museums in the world is always very busy. Plan your visit accordingly, and book your time slot several days in advance.