That's an interesting and revealing review of the 10-22mm by Bob Atkins, if you read between the lines.
Bob gives the impression this lens is equally sharp in the centre from f3.5 to f22, with just a slight increase in sharpness when stopping down to f4 and then f5.6.
However, it beats me how this lens can be considered sharp at f22. Well, it doesn't quite beat me . If it's as sharp at f22 as it is at f5.6 or f8, then it's clearly a soft lens, considering that the 20D is Canon's highest resolving dslr and also considering that smaller formats perform worse at large f/stops.
I don't see any other explanation for this lens being sharp (a relative term) at f22. Maybe someone can help me out here.