Exactly what do you mean by what is it like? I'll try to answer as best I can think to, but if you have a more specific idea I don't cover, just let me know.
I've cruised out of Galveston twice. The water is dirty. You will see oil rigs out in the ocean for at least the first 10 hours of your cruise. The dock itself is a small area, easy to get around. Parking is very close to the pier. You can park in either "official" cruise line parking or the lot across the street. They are the same price, but the lot across the street pulls up to your car and takes your luggage and everyone in the party at the same time to the ship. If you park in official parking, you have to first drop off your luggage and at least one passenger to wait with it, while the driver parks the car and hops on the shuttle to meet the rest of the group. Both are quick, it's just a matter of preference.
The port area is kind of neat. historic area with old buildings for quaint shopping. Not really your typical souvineir shopping. Lots of arts and craft type items, as well as upscale jewelry and homemade jams and the like. All of these shops are within easy walking distance of the ships. Less than half a mile. Not much else to do in the immediate area though. If you want to drive around the island there are some fun activities to pass the time. The Boliver ferry is free and crosses to the Texas mainland. You can drive on and off or you can walk on, ride over and back, and walk back off. This is what we always do. We have seen dolphins swimming along with the ferry 4 out of 5 times. The seagulls follow the ferry the entire time. If you bring bread or crackers you can feed them. It's kind of an Alfred Hitchcock kind of experience though. There are signs all over telling you how to get there. The island is small and laid out in an easy to navigate way. There are also a set of three pyramid shaped musuems and exhibits. One is rainforest, one is aquarium, but I don't remember the third one.
The area right around the cruise terminal is pretty messy and unattractive. The canal is going through a reconstruction and updating and is pretty torn up. A new terminal is being built (might already be finished) for the Grand Princess coming in. It's been a couple of months since I was there, but it was in bad shape. I would assume it would be at least somewhat improved by now.
Hope this covers everything. If not, just repond and I'll try to get back with you in further detail.
The Grand Princess has a 7 night cruise going to Cozumel, Grand Cayman, Majahual-Mexico, and Belize City.
Royal Caribbean has two ships sailing from Galveston most of the year. The Rhapsody sails 7 night iteneraries going to Key West, Grand Cayman, and Cozumel (sometimes they replace Grand Cayman with Jamaica depending on the date). The Splendour sails 4 and 5 night iteneraries which both visit Cozumel. The 5 night also stops at Grand Cayman.
Carnival usually has two ships sailing from Galveston. The Ecstasy sails 4 and 5 night cruises also stopping at Cozumel (and Calica, Mexico on the 5 nt.) The Elation sails 7 nights and goes to Merida-MX, Cozumel, and Belize City.
Celebrity is bringing the Galaxy for 11 and 12 night cruises to the Panama Canal. Her stops will include Cozumel, Costa Maya, partial transit of the canal, Cristibal-Panama, Puerto Limon-Costa Rica, and Grand Cayman. Adding Jamaica on the 12 night itenerary.
Also if you are interested, the Norwegian Sea sails from the Port of Houston just a little north of Galveston. She sails to Cozumel, Roatan-Honduras, Belize City, and Cancun.
As you can see Galveston is becoming the up and coming port with many ships and lines to choose from. Very exciting!
I think it is $60 to park for a week.
I have sailed Carnival and Royal Carribean from Galveston and it was very efficient boarding - much better and faster than Miami ! However, I have heard that Princess has a few kinks since they are brand new there. I hope they get it worked out before our 11-27 sailing on the Grand.
Go to the Strand and eat at Guido's Seafood if you are there a night early or for lunch after disembarkation - it is a Texas tradition!!!
We cruise a lot more often now that Port of Galveston hosts cruise ships - by eliminating air fare our vacation $$$ go a long way!