I've never seen it completed while the game was still competitive, but I've seen people get really really close. The biggest issues seem to be with the small area above the Black Sea and the Balkans.
The area above the Black Sea in particular is vulnerable to the Polish bonus, and the Russian bonus. In fact, there are several really good choke points on the far right side of the map that can keep an Ottoman player from ever completing the bonus, so long as a Polish or Russian player wants to hold it.
The Balkans are threatened by the Spanish player and the Austrian player, as well as the Polish player. In North Africa the Ottoman player has several choke points from which he can defend against Spain, but the Balkans are wide open to attack from a large number of places.
If you assume that the various meta-bonuses of Russia, Poland, Austria, and Spain are not complete, then the Ottomans becomes a lot easier. At that point the game really isn't competitive anymore, so that goes back to my first point.
did anybody complete the ottoman empire in the map Europe 1600: 5/18/2012 13:34:26