Really promising add-on, already has many features that were lacking in Vimium that had always annoyed me.
Love how customisable it is, from keybindings to the colour of the hints.

Some features that it would need to make me switch fully over from Vimium:

-bookmarks and history bar (the existing tab bar looks great so I think these will be good)
- ability to disable specific keys on certain websites, or at least integrate with a page's existing keyboard shortcuts.

I see these are already on the upcoming feature list, how exciting. This could be huge. Definitely has the potential to be far better than Vimium when it is fully operational.