Depends on what yardsticks you're using to measure. The campus is surrounded by historical buildings, which require many permits and special dispensations to change or restore. They're working on a building right next to the admissions building right now... but since it's been designated "historical" (as most of the original buildings are), it has been a long process.
I just went on a tour of the island this past weekend (not all of the island is accessable to civilians yet), run by one of the VP's of the school (and former Navy employee at Mare Island), I think it's beautiful. If you appreciate history and the grace of very old buildings, and have an imagination with an eye for the future, you'll like it. If you don't, you'll wont. Very simple.
For example, I saw the first military building built on the island, from 1857, with some really amazing masonry. The Mare Island Naval Shipyards cemetary, which (along with others) keeps 3 medal of honor winners (one from the Boxer Rebellion!), a senator, relatives of Francis Scott Key, and 6 Russian Sailors who died saving San Franciscans in the Financial District fire of 1863. I love stuff like that.
I got to see the memorial that honors every ship and submarine built at Mare Island... including the Robert E. Lee, the Saginaw, the Skate, and various very historical vessels. I saw the view from the top of the island, near the 11th hole of the golf course that borders the school's 40 acres of the island (in the photos attached, the school is behind and in the midst of the large stand of trees), and I watched part of the San Francisco yacht fleet returning home after a regatta sponsored by the Vallejo Yacht Club.
Are all old buildings beautiful? No. Is there a lot of work to be done, and a lot of work BEING done. Absolutely. The school isn't in charge of most of the island... the state of California is in charge of the historical bits, and much of it is being refurbished and sold for a LOT of money by a little (ha ha) developer called Lennar.
Do I really care what the place looks like, now that I attend? Not really, I've got better things to worry about. But then, I'd rather have an old station wagon that ran like a porsche, than a porsche that ran like an old station wagon. It's what's inside the school that counts.
A few interesting Photos (and a copy of an old photo) for you. The hospital is not used, but I like driving past it every day... it was used for filming Patch Adams.