Looks like both segments are on the 332 which I believe all have lie flat seats. I wouldn't hesitate to use C on that plane. If 772 then I would say depends heavily on the price, the seats are absolutely craptastic, but if it's 2k or 3k cheaper then it's certainly livable. C seats on the A380 are great but I think that plane is only running the LAX route at the moment.

As for CZ in general, they're really not so bad, food quality in C is decent, service is fine for a Chinese carrier. CAN isn't the greatest airport for international transfer, looks like you have 6 hours. The wait for transfer immigration sometimes gets long but you have plenty of time. I've waited an hour before early in the morning. I've never used it but supposedly the CZ lounge in CAN is pretty good. If you're seeing a decent savings over other ST airlines then go for it, if similar to other carriers, I might go for the best schedule (assuming 332 on both segments).