The good: Marketed as a "luxury capsule hotel", rooms are much larger than the typical Japanese capsule and furnished in a clean, bright, minimalist style befitting its name. Has a basement bar serving good food in the afternoons and evenings and a basic but decent breakfast. Very well located, just seconds from Ningyocho station, served by the Hibiya and Asakusa metro lines. The Asakusa line provides a direct connection to both Narita and Haneda airports.
The bad: As required by Japanese law, there are only curtains separating rooms from the corridors. My sleep was interrupted at 6 am by a ringing alarm that went on for 15 minutes and at 7 am by a loud cellphone talker. The second time I went to the receptionist for help, but she declined to speak to the guest, saying it was "ok" to talk in the rooms! It's common sense that you shouldn't do this in capsule hotels, and the hotel's own rules also forbid this. And yes I was wearing earplugs.
After trying in vain to go back to sleep, I went back to reception at 7:30 am and finally she put in a word with the guest. The inconsiderate guests were not the hotel's fault, but it was inexcusable that the receptionist refused to enforce the hotel's own no-talking rules in the first place.