One thing I never gave a single thought about was the dedicated button, depending on how you hold your phone, it can be a pita to actuate! I may go against the status quo, but I really like the soft keys of the S2 and the more centered back button of the S2. Time will tell, and those are some trivial things, but some very often used items.
For those interested I used Saferoot, and ran it twice in order to get busy box installed. I must have toggled a security setting "Verify Apps" as it blocked the install on the first attempt. Phone came with 4.3 MK5 installed and I honestly couldn't tell you how the battery is as I have had my hands on it non-stop. I much prefer the older Samsung charge/USB cords, the new ones are extremely stiff. I forseee more charge port problems