It's difficult to judge a Chinese buffet in Italy, because there are very little competitions and…read morefrankly, you're in Milan!
But it's easy because I'm a former Chinese buffet expert so I can break it down to you: there are some good items here, many average ones, and some really horrific.
Good ones to try: large shrimp, beef, or anything that is from the grill area. Their fried rice was above average (but don't fill up on that since you'll get full really quickly). Seafood salad (by the salad bar), pineapple (in season) and stir-fry shrimp were also good.
Average: everything else, minus the horrific ones below.
Horrific: sushi (not as fresh/cold as I'd like), any of the dim sum items, stir-fry section (not to be confused with the grilled section, which you don't choose sauce), teriyaki chicken (overcooked), spare ribs (overcooked)
Having said that, $20 euro per person isn't that bad, considering the variety of things you can get.
Pro tip: even if you put 6-7 large shrimp on your plate (from the grilling section), they will only bring you 3-4. So separate them into multiple plates with something random (example: if you want 7 shrimp, put 3 + slice of beef on 1 plate, and 4 + slice of chicken on another plate).
Pro tip 2: gelato is $1 more