Sure, UI/UX can be a whole science, but in the end, a lot of it boils down to preference. As you can see when reading through this comment thread.

My personal biggest pet peeve: I hate, Hate, HATE that they changed the default behavior of clicks into the address or search bar, from simply "put the cursor here" to "select all". Oh my goodness, do I hate this, even after all these months. It breaks a fundamental behavior of text fields since, I don't know, the beginning of time?

Even today, I don't know how many times I keep inadvertenly deleting the contents of my search bar when all I want to do is add another term at the end. My brain is probably just too old to learn something new, I guess.

Also annoying: with the new add-on system, you cannot even write a plugin to restore the previous sane behavior.