Pros
Flexible schedule. Access to a really huge supercomputer. Many bright people, you can learn a lot from them.
Cons
Average rent in Barcelona takes almost 80% of the median salary in BSC. Raises are almost automatically denied under the argument of BSC being a public institution and therefore being subject to "public regulations", or other budget issues derived from how European projects work. This does not seem to apply to management, as they may earn 10 or 12 times the salary of some of his employees. There are (or were) productivity bonuses that are unilaterally split between corrupt team managers, leaving 0EUR for the rest of the team. It is nice to have research teams with managers with Rolex watches in their wrists and researchers having to share horrible flats with other three people outside of Barcelona while living in almost poverty conditions. It is impossible to have a fixed contract. In fact, many store clerks and janitors have more stability and better salaries than some BSC personnel. Most people (especially seniors) do not care if you are not able to speak Spanish, so prepare yourself for having meetings full of people discussing your own work in a language you don't fully understand in front of you. If you complain they will say that it is tiring for them to translate everything they think to English (as if it was easier for other non-native English speakers like myself). They also speak Catalan sometimes, a local language, which is even harder to understand for most foreign people. A Ph.D. is mandatory if you want to progress inside the company. If you want to stay in BSC you must choose between spending 4+ years earning a sub-sub par salary to have the opportunity to have access to a job with a subpar salary when compared to what the regular industry can offer to a person with your experience and background or have a subpar salary in a dead-end job with no prospects of improvement thanks to the academic barrier introduced by the PhD. Many people who would be labeled as Senior Software Engineers in other companies may be labeled as Junior Developers or Junior Research Engineers (whatever this means) in BSC. PhDs programs offered by BSC are just a bureaucratic thing. I've been in like 15 Ph.D. defenses and all of them got either Excellent or Cum Laude grades. They are not a challenge and many do not have any kind of original research contribution. Many of these PhDs are just a compendium of all the B.S some poor soul had to do while working for some academic dinosaur. PhDs are used by BSC as an excuse to have really bright people working in horrible conditions, and many of these people get fired or do not get any kind of offer once they finish their PhDs because BSC knows that they have no way to keep them enslaved in horrible conditions anymore. In other words, BSC is just a vampiric institution full of people who have been lying and taking advantage of the inexperienced and will of many young researchers for many years. Many of these people may look like prestigious researchers with many publications, but don't get fooled. They are just vampires who cannot do anything by themselves. They just steal the credit for the work other people did under their orders. Academic ethics are not a thing for some people here. You must be really careful about managers and some senior researchers, as they may try to steal your work whenever possible. Some other people just lie or manipulate in their experiments, and therefore produce pure academic B.S. This is known and accepted by many management people, as they know that this way to proceed is never punished but rewarded, given how academic metrics work. I must say I have experience in really harsh and competitive private companies, and even in these companies, there were fewer vultures and rats than in BSC. Some supposedly senior researchers clearly have no training or knowledge of the academic code of honor, and many have no actual technical skills. In fact, many of these researchers probably cannot work in an actual research center or in the industry, as they are mediocre as hell. However, some of these researchers may seem good or even excellent thanks to the artificial academic bubble.