Removing icons from the menus has been one of the most puzzling decisions they made. In the year or so since its removal, using their menus has been a real struggle, and I can see there's even an entry on Mozilla Connect Ideas for it: https://connect.mozilla.org/t5/ideas/bring-back-menu-icons/i...
As for the 'curvy' tabs, I can't say I was a fan of it, even in Chrome, it feels like a waste of space and draws attention to it. The straight tabs, even the 'button' tab is a lot better in being out of the way.