Very fun scenario.
I'm playing as the Venetians, the scenario is half over, and have managed to take the cities in southern Greece from the Latins (conquered them utterly), whilst bribing the Lombards into keeping the Papal States off my back long enough to do this. This Hospitalers have been little trouble (I've made peace with them by this point).
The Ottomans are conquering everything in site, though Constantinople still stands! I am gaining them on points, slowly, and IF I can manage to take Constantinople myself, and IF I can keep the Ottomans off my back the entire time, I might be able to catch them, though even this will be rather difficult...(the Ottomans are furious with me).
I'm not regretting the research of Diplomacy, as this has proved invaluable until I can build up a bit (as the Venetians you start out needing to build up). This is an interesting and challenging scenario to play as the Venetians, fun to play, and the graphics give it a nice flavour.