I think Sucre gets a bit of a bad rep because it's "another colonial town" and basically it is. I still liked the town because it grows on you. It's very laid back, there are many foreigners coming here to learn Spanish so you always run into friendly people and start to see familiar faces. When I made Sucre my base for a few days to explore not only the town itself but also the surrounding area I also took advantage to take some Spanish lessons at my hostel.
There was also a big banner that they are planning some celebrations for the 20th anniversary - that's still 2 years to go - but it shows how they really care about the title of being a UNESCO town.
The best view is from the roofs of the San Felipe Neri church. The church itself isn't that great but it's worth it for the view and the sisters were again really, really friendly. Spend a lazy afternoon in the central park where kids like to roam around and everyone else likes to have a rest on the benches.
So I almost feel this place is worthy of the title not for the buildings but for the feel you get.