It's not worth visiting and it is worth visiting. Now let me explain.
The Palace of the Governors on Santa Fe Plaza, originally built in 1610, was the base of government for about 300 years. It's worth visiting to see the Indian crafts people sitting in the portal - the covered porch area in front of the Palace - offering their goods for sale. Only Native Americans are allowed to sell in this coveted space, and all goods are made either by the individual or their family members. Sellers settle into a three by four foot space with their jewelry, turquoise or pottery displayed before them as tourists slowly wander by.
The Palace itself, New Mexico's history museum, is not worth a visit at $7. It's dusty, disorganized and failed to touch on the bits of New Mexican history I was curious about. Other than brief mentions, I didn't see much on Kit Carson, the Pueblo uprising or the Manhattan Project. The most interesting features involved the building itself: a series of photos showing the Palace over time and exhibits highlighting features of the original structure uncovered during restoration.
The Museums of New Mexico DO offer a good deal... a four day pass to visit 5 museums in Santa Fe for $15. The pass includes the Palace of the Governors and Museum of Fine Arts downtown and the Museums of Indian Arts and Culture, of International Folk Art, and of Spanish Colonial Art on Museum Hill.