Galveston was once a major city in early 20th century as a port city, but Houston became the major hub now. It was a vacation spot for a while where cruise ships sailed out. Hurricane in 2008 destroyed some of the infrastructures, med school closed down temporarily during that time.
It is not a nice city anymore. Run-down in some parts, mostly suburbia-like, otherwise island/beach/swampy. Better go for UT Houston, San Antonio, or UTSW Austin (community hospital), which I'm guessing would be comparable to UTMB program, which as an institution seem pretty respected in Texas.