Pros
There is a nice environment in the Research department, everyone is willing to teach you and explain topics topics in economics/econometrics. The pay is nothing bad compared to other internships in Spain. I was given some interesting projects to work on.
Cons
During my time at BBVA they implemented a policy of hiring lots of interns. While I was busy most of the time, some other iterns had nothing to do, and spent the whole day in the cafeteria or roaming around the offices. It was sad to see that. The organization is highly unefficient, it took months for the IT department to give me the software i needed to do my job, some interns spent months without a computer. IT also managed to get me both a Python and an R license, so I could use them legaly, how did they do this still boggles me.