A very nice add-on. I've been spoiled with many years of Vimperator, Pentadactyl, and Vimium (in Chrome.)
Vim Vixen is on par with those venerable add-ons for reliability & stability.
Users should be aware they can configure the "hint" keys are configurable! Maybe they were before, but the JSON structure omits the item when it's at default value. The config form provides a field for the setting regardless. In the JSON, the "hintchars" element resides in the "properties" block:
"properties": {
"hintchars": "asdfgqwertzxcvb12345hy6n",
"smoothscroll": false
}
Woo hoo -- Kudos to Shin'ya Ueoka!