The mobile navigation bar seems quite useful for first time users, but the space seems quite spread out, in comparison to say, samsung's default browser. On the other hand, Ive had to inform a lot of non-technical friends and family members of firefox's extension feature - many people dont click on the drop-down menus. Most people I've shown extensions switch to firefox entirely, since its an incredibly useful feature, but one hidden from most users.
I think it would be a good idea to make a dedicated extensions button on the navigation bar - its a killer feature and should be more up and center! I understand why extensions are a little difficult to find, since they tend to be an 'advanced' user feature, but I think mozilla's "recommended extension" feature removes the danger for most non-technical users.
In addition, it may be a good idea to make the share and refresh buttons more distinctly "button like" - theyre really easy to miss! I wouldnt be surprised if most users just ignore them, in the same way many people dont realize they can click on the connection security lock icon.