Avantages
English-ish environment. IT is mostly English but lots of important functions like HR are mostly Japanese. They are trying to create a silicon valley spirit in Tokyo. Free food but you quickly get tired of the same menu/rotation. I put 5 stars at work/life balance because I could literally do my daily tasks in less than 1 or 2 hours. It's a great place if you have no ambitions. You can get promoted even if you do a mediocre job (although raise is virtually non-existent). If you are a foreigner, there is no expectation/pressure to do overtime. Company is somewhat LGBT friendly.
Inconvénients
I honestly believe that management has no idea what's going on. This is a boat sailing without a captain and without a destination. There is no real innovation although the president invented the word "Innoperation" (from Innovative and Operations) to describe the company. I'm not sure if the company is doing "Innoperation" but it's clearly inoperative. Salary is lower than most places (I call this the "non-native speaking tax" so I guess it's understandable to some extend). Your starting salary will remain almost the same even if you do well. There's the official HR evaluation system and then there's the "informal system". There's "church" to attend on Monday mornings where the CEO talks pretty much non sense about his vision (or lack of). He tries to dodge questions that he's made aware of in advance (I participated, your questions are pre-screened and it's all smoke and mirrors). Don't expect help from managers. They "manage" (whatever that means) and spend their days in meetings. The turn over is crazy high. You might end up being the senior in your team with practically no knowledge on how to do/fix things. Although the company claims to be diversified, there is clearly a wall between locals and foreigners. It may or may not be ok for some people.