They were fun to fly in because of the stigma of it being a 747, but the actual experience in and of itself was nothing special in my opinion. Actually I find them not very comfortable. I'd love to fly on one again because its been quite a while since I was on one, but for flying on a regular basis there are other planes I'd rather be on.
Lufthansa flies a number of the 747-8i aircraft. They and another airline I cannot remember are the only ones who bought these planes. Boeing is not making anymore except for the next Air Force 1 aircraft then after that the line will shut down.
On the cargo side there are still some 747 including the 8i.