You can spoof the user agent in Firefox and see for yourself. It's _really bad_, bordering on completely unusable (at least, it was at launch). Inbox uses a lot

You can spoof the user agent in Firefox and see for yourself. It's _really bad_, bordering on completely unusable (at least, it was at launch). Inbox uses a lot of animation, and having that animation run at a couple frames per second makes an exceptionally poor user experience. If I worked on Inbox, I wouldn't feel comfortable releasing anything like that on Firefox either, even if it was gated with a disclaimer. It wouldn't reflect well on Google or Mozilla.