With a half year delay I report my experience in 88L on CDG-JNB: I absolutely hated it.
The seat would be fine for 2-3 hours daytime flight. The legroom is good enough to actually sit and not touch a bulkhead with your knees. So initially when I settled in I was a happy camper. However because of a bulkhead you've got absolutely no space to extend your legs. Like totally no-no. I would say standard seats provide a way more space in that regard. When I fly Delta A330 or KLM 777 in a bulkhead row the legroom is sufficient enough to extend my legs against a wall which makes a perfectly comfortable set up. That didn't work with 88L as well, as a bulkhead is so close I think only a 3-4 y.o. child could extend legs against a bulkhead.

and yes the seat is narrow. I would say it's good 2 inches narrower than a standard seat.

I'm 180 cm (5.9 ft).

So It was truly miserable experience. Honestly it was my personal second worst longhaul flight ever.

Overall except an extra side box which is of course convenient I have nothing good to say about AF economy on A380. The plane feels ancient. No wi fi. No power. Tiny old tv screens with poor quality displays and limited selection.

If you're already booked on A380 (otherwise I strongly recommend against it) I would suggest to have a look at economy seats on a lower deck: 11A, 11L, 34D and even 45A-C and 45J-L seem to be a much better choice.