I didn’t mind the addition of Pocket because I didn’t use it. I didn’t mind the addition of Hello, as I didn’t use it. I didn’t mind the removal of the original themeing ability, which was far superior to what we have now. Didn’t even really care about the removal of Flash either. What I do mind is when you ignore user feedback, push out a release, break every existing theme and make things look incredibly stupid, then continue to ignore user feedback.
Your new rounded theme design is horrible to look at, and it’s not something I want to continue using. The new tabs are oversized with needless padding and disconnected from the UI itself – they feel out of place. Your menus take ages to open and render correctly with the amount of Fonts I have for design and testing. Everything feels like you designed it for mobile, tablet or finger input – but this is your Desktop browser.
Though in the end, this decision doesn’t surprise me. You haven’t exactly made great decisions in the past, and you continue this path even now. Only a matter of time until Firefox is completely forgotten, and only Chromium remains.