I tend to hold my phone in my right hand and frequently use the thumb ofcthat hand to navigate. However with the new native UI, I have to reach all the way to the top left-hand corner and that's just plain uncomfortable. The old UI was much better as you could easily hide it, it felt a much more natural way of accessing tabs without taking up screen space and the new tab buttonwas much more accessible. For me this is a blocker to using this version on a daily basis.
The Tab UI has just changed to the other side of the screen. Now I've played with it, I'm going to argue that having the Tab UI at the top of the screen is going to end up uncomfortable for folks with larger screens (like the Galaxy S2). With the previous stop/reload button there, that was fine, you don't hit that much, however accessing the tabs seems much more frequent, and hence hitting that location just isn't as convenient, and causes unnecessary stretching (and I have big hands).
related to bug 702959