Congratulations to Chinese fans for finally getting a driver in F1.
Zhou is probably not in the world's top 20 drivers but also probably not far off. He's one of those "okay" prospects that we don't expect to develop into a star, but also wouldn't expect to disgrace himself. He's just a solid, tidy pro driver. Still just 22 years old which seems perhaps surprising as we've seen him in feeder series for a little while.
I would expect a slight dropoff in performance from Giovinazzi - as unexciting as Gio has been, it's easy to forget he came into F1 with some pedigree behind him, had looked the equal of Gasly in F2 as his team-mate with less experience. They are also swapping a driver with 3 years of F1 experience by a rookie. However, the potential pool of Chinese funding that opens to them clearly justifies it, specially given they'll have a very good lead driver in Bottas, likely an upgrade from a 40 year old Kimi. This is also the year where they can afford to swap both drivers, as the cars will be completely different and comparing it to the last Alfa car is not as relevant. It's the right call for the team.