They are definitely not that bad. If you are on the 77W, I can safely say that it has the most comfortable economy seat that I have ever sat in. The IFE is very limited, but it still okay, just not EK or SQ level.

I generally find that Asian food is one of the safest bets on a plane, so I usually find the food on Chinese airlines to be okay. There will definitely be no shortage of water, so I wouldn't worry about that. I know a lot of people bash the Chinese airlines, and it is true, they are not great, but they are also not that bad.