Barcelona has such a wide variety of choices for travelers! There are beautiful cathedrals, bizarre, yet fascinating architecture (Gaudi), historical sites, stunning beaches, music, museums, shopping, etc.,. The Metro system makes it easy for budget travelers to get from site to site. There are hundreds of tiny restaurant/bars to sample tapas and local dishes. You can eat well on a budget!
Barcelona is a unique area within the country of Spain. They have their own language, history, and customs. Invest in a good guidebook such as Rick Steves' Barcelona and research well. Plan to spend several days here. It is worth it!