Lived there for the past six months, I loved it!
Pros:
Amazing public transit, fast and cheap (€8 for the month as a resident). Great food culture, also inexpensive. Very walkable city w/ such pretty streets. Many museums and art galleries and other community art spaces all over (old industrial complexes turned into small, free museums). Fantastic public parks (some massive ones right in the city center) The list could go on.
Cons:
None that I can think of.
Well, you should be able to speak Spanish…