Agree with a lot of the comments above, but the one that hasn't been mentioned and I LOVE is the buddy dining - the thing that Mrs BAECAddict and I enjoy most about a flight in F is being able to dine facing each other. I know you can currently sort of do this in CW, but actually having the table set up for two and then dine with a view is great fun. I should mention that this is best enjoyed on the A380 where there is LOADS of space and it also works quite well on the 777 which generally has enough space. The 747, at least rows 1 and 2, is a different matter and not recommended. We have avoided the 787 so far because the F seat doesn't have this option.
Otherwise, the better service, generally better food and drink and direct aisle access are all worth the extra plus CCR access is also a bit of a haven since the Flounge can get pretty busy at T5.