The H8i are gorgeous, on-ear, active noise cancelling headphones with premium build, solid sound quality, and premium looks: they are definitely fashionable. On-ear headphones, by virtue of physics, are just not as effective at blocking noise as over-ear / around-the-ear models like the Bose QuietComfort 35, so I was surprised to find that the H8i were extraordinarily effective at blocking low-frequency sounds, nearly as good (from memory) as the QuietComfort 35 and better than my over-ear, ANC wireless Plantronics BackBeat Pro 2.
However, I found that achieving that level of noise cancellation with on-ear headphones comes at a cost, at least for my large ears: they hurt noticeably after about 15-20 minutes, requiring me to spell my ears by briefly taking them off and giving my ears a break for a minute or so.
I also found the default sound to be a little warm, substantially more so than the wired B&O Beoplay H6 I previously had, but the app on my iPhone (it's available for Android as well) has a simple, consumer-friendly way to tune the sound graphically -- no traditional EQ sliders at specific frequencies here, so this may be a minus for audio nerds who are familiar with traditional EQ controls. The equalization is stored on the headphones themselves, so it works system-wide on the paired device, rather than being limited to a specific app like Spotify's EQ controls in iOS, or like the simplistic EQ presets built into iPhone that only affect the built-in app.
Unfortunately for me, the pain on my ears physically from the clamp and pressure on my big ears was too much for me to keep these, and I went back to my Plantronics Backbeat Pro 2, which are more comfortable over-ear headphones. Still, for people with smaller ears, these may work for you, so I advise anyone considering a purchase of the H8i to try them on for a while in-store first!