Agreed - for a top club, he would be a valuable squad player. Nothing more.
Gez is right that the needs his engine but that;s an indictment on the team rather than bigging up the player. When fans talk about a players work rate as his number 1 attribute, that's when you know you're dealing with a limited player. Henderson is one of those players who is suited to a team of superstars who do the moments of quaality in a game. He is not someone who can change a game, dictate tempo or ultimately grab the game by the scruff of the neck.
This isn't me slating Hendo - I think he's a good player who can improve (he really needs to improve!). But if we want to get to the next level, then he will be a squad player. If we buy a quality DM, then I can the DM alongside Can and that would form a quality partnership.