It's just a big city, if you want to see any of the Gaudi sites they are well spread about and better to be seen on a tourist bus, but be aware there are long queues. you can book one on the ship but it will be expensive.
Great for shopping, booze (compare prices) is very cheap but be prepared to pay normal price for electronics and perfume. The sites can be booked local and will save you a lot of money. English is spoken, all signs are in English and the money is British pound. You will pay over the odds with Euro.