Enjoyed an overnight stay here last month and would echo what others have said. New property and so the physical plant is very nice. Friendly staff. Solid breakfast buffet which is free for Gold (as opposed to the Sheraton or Westin where you have to be top tier to get breakfast). Location is fine in that the center of Zagreb isn't far by tram from any hotel (although the Westin is better for the main museums). My upgrade was to a corner room on my floor which isn't bigger, just nicer views.
Nice to hear about the taxi option, since with the dollar up against the Euro 200 Kuna is about $30 which is reasonable for the ride and is simpler taking the tram to the bus station (or walking as I did) and then the bus to the airport for a total of about 40 Kuna per person.