It's hard to make generalizations because this is a large company with many different work environments but generally speaking...
Built-in Japanese cultural expectations could be a con for some. For example in Japan, you are expected to do your job. If you don't know what it is, it's your responsibility to ask the right questions and figure it out. Whereas in America you'll hear people make excuses like "I didn't know" or "nobody told me to do that." So there is a fundamental cultural gap built-in that makes the company a poor fit for some. And of course there is a language barrier in some workgroups. Especially there is frequently a gap between expats and local staff simply because a lot the conversation is in Japanese between expats. They are not hiding anything but the information flow that would normally get shared by working side-by-side in an office space doesn't occur. They may not go out of their way to share things that are going on and engineers don't bother to ask.
Go getters that want to take initiative may get frustrated at the amount of effort and speed to make change happen. It can be done and Management welcomes it but it's not easy.
Work-life balance can be difficult for some, especially for those that are conscientious. Those that are not conscientious have a great work-life balance because they have no qualms about putting in their 8 hours and leaving, letting their co-workers or the expats clean up their unfinished business.
Desktop workstation technology is typically behind but for most work that is email or MS Office-based it's fine. Global systems are typically old and behind the times as they are in any big company.
For those in Japan-related positions there can be intrusions on personal time because you need to talk with Japan either very early or in the middle of evening (but the expats bear the brunt of this).
As others have mentioned there are some mediocre people here. As a manager I can say that's true. In a tough labor market it's not easy finding good people so it's better to keep those people around rather than somehow hope I'm going to be able to hire better people that will adapt to the corporate culture and stick around. I will say, though, those less-than-stellar people don't get the bonus, merit and promotions that their high-performing peers get.
The compensation system is too opaque. The reviewer complaining about people getting paid "below average" doesn't understand the system. There are defined salary bands and the fact that many/most people are paid below the midpoint of the band doesn't mean they are paid below average. If you can clearly show you're underpaid, you can get a market adjustment but typically people just say that anecdotically with no real evidence to back it up. As a manager I usually have to look at the wages we are hiring at to tell me if this is really the case. Again, the point being that where you are in the salary band is not particularly relevant.
