Messi is a quality player and a great dribbler of the ball - he can keep the ball close to him and change direction quickly because of his short stride/legs. Lets face it though, you could have put any footballer in the Barcelona team of the last 10 years and they would have looked half decent. Messi had an exceptional group of players around him which helped him to create chances and play with a lot of freedom.
It's similar to Rooney playing in midfield for me, he pulled it off all of those years at Man UTD largely because of the players around him and generally inferior opposition, once you put him in a team that is not so good (ie. England or Everton) he's bang average there. I'm not saying Messi is a bang average player just that in order to excel he had a lot of support from the rest of the team.