Last month we did a round trip from Beijing to Europe in Air China business class. We were pleasantly surprised by the service on our way to Barcelona (rivaled best service on flights in Emirates First class- which I know is an entire different discussion). Food was good, wine selection was limited. Return from Frankfurt wasn't as nice. Service was ok, but a little robotic. Food was surprisingly good, wine refills were plentiful but the wine was nowhere near the proper temperature. The only really bad thing was the cabin temperature- we were borderline sweating the entire flight both directions, there were no individual air nozzles to even provide air flow. For many reasons we may end up flying them back to US later this year and are already looking for usb fans to use during our next flight with them. Cabin temperature aside we were pretty happy with the flight. (and although we are learning to speak Mandarin, we had no problem communicating mostly in English during the flights).
On a side note, don't expect much from the lounge in Beijing. It's an escape from the terminal, but really isn't all that great beyond that.