Everything Good in Firefox Android.
But here are some reason not to make default browser in mobile...
1).Allow to set custom font zoom for every other websites in Android Mobile
Like for one website I choose 90% font size and for other i can choose for 110% font size.
Issue : Firefox set one font size for every websites.
2). Shortcut: On home automatically lots of shortcut added, that i have been only visited on site, you can remove shortcut with bookmark (if bookmark ui is small like shortcut )
Or give more buttons to add Shortcuts
