Avantages
1. Good place to work in if you are a mediocre worker, since it is almost impossible to be fired. 2. Life-long employment, regardless of performance. 3. Lots of vacations.
Inconvénients
TL;DR: Typical Japanese company. The only reason it exists is because it is a Japanese company, and Japanese only deal with other Japanese (they are very nationalistic). 1. Hierarchical, with promotion based solely on years served in this company. 2. Glass ceiling for foreigners (in fact, you will be passed up in favor of Japanese). 3. Low level of technical skills, even with their 'best' researchers. They are adept at using buzzwords without knowing what it means, or how to implement/use the technologies. Ultimately outsources the projects to cheaper (but much higher skilled) Southeast Asian contractors when they can't solve the problems. 4. Very very low compensation by international industry standard. 5. Uninteresting projects. 6. Training is close to useless. "Training" aims to make you conform to the Japanese corporate culture (mainly just writing daily reports on how many hours of meetings you attended, how many words you typed in your report etc) instead of transferring technical skills.