Walcott and Downing are definitely better than him, and probably Young as well if he was to be played on the right
No, no they are not better than Milner in any way shape or form.
edit: To be clear. Milner is a complete player. Downing and Young have major gaps in their game (downing cant tackle and young has the attention span of a goldfish).
Walcott is a different case that is debatable.