On iOS, both iPhone and iPad, the tab bar is very too narrow vertically. It is quite difficult to accurately tap the x to close a tab or the + to open a new tab. I would love to have an option to make the tab bar taller so it would be easier to use, especially for those of us who are older with less than steady hands.
I would also second the suggestion from some others to increase the contrast between the active tab and the inactive tabs to make it clearer which tab is active. Perhaps make the inactive tabs a little darker and the active tab a little lighter. It just needs a little more contrast.
And please never ever go the way that Firefox went with their tabs and disconnect the active tab from its content. I hated that change! That was the reason I stopped using Firefox!