The first impression of this boot led me to think that Adidas had played it too safe. The profile and feel of the boot, despite an updated paint job, seemed far too similar to the last adiZero. The slight texture added to the upper seemed too minuscule to truly affect play and the painful break-in did not help my opinion. Factor in that I was testing and really enjoying the leather version, and I was not full of praise for this boot.
However, after (finally) breaking the F50 in, I really started to see that Adidas have made some key changes that have actually improved the boot. The boot fits much better in the mid foot and the increased size of the sprint-frame is definitely the contributing factor. The heel has also been changed slightly and I feel more secure in this F50 than in the last one (which is very important for a man with a past filled with broken ankles). And, despite seeming too recessed to truly affect your play, the pattern on the upper provides a little more grip on the ball in all conditions.