I wouldn't say he's inconsistent, he's on his game for 80% of the season so that is not inconsistent. It just takes him a long time to get match sharpness after injury or when he's not played for a while (ie when a World Cup is about to start), but on his day he in my opinion he is the best striker in the world in what he brings to the table, there's no one like him who can do what he can do, hence why he's generally the best allround player on FIFA games, i know its a bit silly bringing a computer game into this, but you know what i mean? He as these quality's, people can see them and they've been made into a game that tries to be realistic as possible.
Saying that i do think he as a expiration date, i can't see him still being a WC player at 32/33, certainly he won't be doing what Giggs is doing now.