I have only seen XANADU, PASSING STRANGE, and IN THE HEIGHTS. So the comments below pertain to just having seen these three nominated shows:
XANADU -- The BEST overall production. Solid score, solid book, solid acting. There are NO holes or weak points ANYWHERE. Generally speaking, the only reason why people may not like it is because of WHAT it is (not HOW it was executed). It's a show that makes fun of itself and its genre. For what the show is and does, I think it is BRILLIANT! PLUS, you have some great unique add-on factors: rollerskates, on-stage seating and interaction, Kerry Butler, Mary Testa, Jackie Hoffman, Cheyenne Jackson, and one of the BEST ensembles I have ever seen.
PASSING STRANGE -- understanding that it was PERFORMANCE ART, I thought it was a solid book, a strange score (that worked 3/4 of the time), and OUTSTANDING performances. However, these performances were performed in a strange void. A void that obviously confused many, but also won over many. Personally, I thought it was mediocre performance art and the only reason why it's getting the attention it is getting is because it is unique to the Broadway scene. It's "cool" to like. The one thing I kept on hating and hating throughout the show was Stew. Until the very end of the play, I just couldn't stand him. He was distracting and irritating.
IN THE HEIGHTS -- A new "flavah" for Broadway yet again. I'll be brief. This COULD have been the best of the season if it weren't for a WEAK book. Usnavi's character sung so fast I missed lyrics a lot of the time. I immensely enjoyed myself a lot of the time, but I equally felt "?" a lot of the time.
So at the Tonys, do we reward extreme rarity/fresh flavah/originality, even though those shows include problems? Or do we reward the overall BEST show of the season which had NO problems?
So if you don't care about the show's structure and writing, then it all comes down to taste.
"The Spectacle has, indeed, an emotional attraction of its own, but, of all the parts, it is the least artistic, and connected least with the art of poetry. For the power of Tragedy, we may be sure, is felt even apart from representation and actors. Besides, the production of spectacular effects depends more on the art of the stage machinist than on that of the poet."
--Aristotle