Rakuten

• One of the few companies available for non-Japanese speakers. (However, be prepared to learn if you intend to progress career-wise. Lots of groups still use Japanese to communicate.)
• Free lunch, breakfast, and dinner.
• Great diversity (though depending on service and departments).
• Chance to work with some very talented people. Met a couple of super-talented people, but they were undervalued by the managers.
• Good learning experience work-wise and technology-wise. (However, some groups are still stuck to 90s tech.)

• Very slow career development and salary raises.
• Low salary in comparison to similar companies.
• Very slow internal procedures for getting approvals. Many internal tasks are very manual, like submitting printed papers and so on.
• Managers are very number-oriented, not daring to take the slightest of risks, and are very uptight.
• Overtime work in many groups.
• Some conservative ways and policies. (For example, once every employee was made to sign a hand-written pledge letter saying we would always wear our name badge on the left side of our chest because it's our only uniform. This move was directed from the CEO himself.)

Take more risk in projects regarding new technologies.

Learn to identify and appreciate talented people.