I have flown the 77 in Biz on CZ. Its really not too bad, but I'm curious what your other options are? If you're actually going to Guangzhou then just take it and don't worry about other options since it's non-stop but if you're going anywhere else I'd look at some better airlines serving the area.

Seats are the old first class seats so they are pretty close to angled lie flat and they have a massive 72" seat pitch. The foot rest was very uncomfortable for me, that was my only complaint about the seat.

I found service to be fine and they were actually very attentive to me. There was a nice mid-flight snack bar in the front of the cabin if you want anything between meals.

The in seat video leaves a lot to be desired, that's probably the biggest downside. I don't know when the 777's will get the new seats but CZ does have some great seats with modern AVOD on the newer A330's they use in Asia.