I was lucky enough to spend a full academic year at UPC as part of the Sicue mobility programme. The syllabus was also well structured, with exams that accurately reflected the material covered in class. In addition, the teachers prepared their classes and made sure that the student learned. In this way, the effort is rewarded.
The UPC is highly decentralized with faculties spread throughout Barcelona and its neighboring towns. In my opinion, it is best to look for accommodation near the university, since it represents a great economic and time saving.
My biggest drawback to this university comes in terms of the language in which the classes are taught. If you are going to study the entire grade (from the first year) you will have no alternative but to learn Catalan since most of the teachers will insist on teaching the classes in Catalan. Even if the study plan indicates that it is Spanish or Catalan, the preferred language will always be the second. In my case, since I was only going to be there for one year and I had classes from the last few years, most of the teachers agreed to teach the classes in Spanish.
Finally, I would like to point out that Barcelona is an incredible city, with an enviable cultural offer. With a lot of multiculturalism and things to do any day of the week.