I guess that it is a matter of tastes.
I did not use the F seat but saw them when disembarking.
They take the same space as on AF but they are an enclosed suite a la EK. Personally, I like privacy in my little cocoon. I dislike profoundly the open concept of the A380 where everyone can look at everyone and the conversations carry.
And they have two rows (total 6 seats), so does not get the claustrophobic feeling of the one-row AF cabin. And they have a big space with bar and canapees in front of the double bed.
The pictures of their F double bed are quite impressive.
https://www.milevalue.com/china-east...-korean-delta/
PS: Food in business class on Chinese airline has really improved a lot, especially Chinese food. wines are still poor on average.. But many of the old cliches on Chinese airlines longhaul are becoming outdated, even if repeated a nausea.