I've been in Texas since 07 and lived in Houston from 2012-2015 so I've had the opportunity to visit Galveston multiple times. My opinion as that it is a cool place as long as you know what you're getting into in advance. If you're expecting white sand beaches with Crystal blue waters this ain't your place.
* Galveston is an old city. Historic with old buildings. Really cool vibe but many places really are haunted.
* Downtown and "The Strand" is a lot of fun. Good restaurants and bars.
* Good Culinary seen all together and most of the food in the Seawall area is darn good and not a lot of tourist traps. Gaido's Seafood, Mario's Seawall Pizza are two of my favorites.
* The Spot is a great place across from The Beach to eat and Drink and if you want a local dive you can go to The Poop Deck. <---- Real Place.
* A big thing to remember is Galveston is essentially a superb of Houston. With that brings some big city problems i.e. crime. You will see your fair share of drifters.
Hope that helps.