to give you a different viewpoint, I loved 100 Years of Magic, as it had a lot of kewl additions:
-Four new parades
-those kewl banners in the parks that light up at night
-Magical Moments Pins
-Who Wants to Be a Millionaire--PLAY IT!! (EXTREMELY popular)
-One Man's Dream (the movie at the end makes this one of the best shows disney has--but it'll make you wanna cry...)
-and I personally think the Sorceror Hat is the best celebration icon yet--it looks amazing at night--just look at the pictures from New Years with the Hat with Sorcery in the Sky in the background--I was quite impressed by it, as are most people--one of the reasons it was decided way back in December that this would be permanent and the official icon for the Disney Studios (if you get those shirts that show the four park icons, they will now have the Sorceror Hat instead of the Earfel Tower)
-you will also get to ride Primeval Whirl!, of course, which people seem to like more and more (theming aside, it looks/sounds fun)
-Animal Kingdom Lodge, my favorite Resort on property
-the moderately amusing Magic Carpets of Aladdin and TriceraTop Spin
-if you are going in 20 weeks, Journey Into Imagination with Figment will be open
So, as you can see, there are several new attractions at every park, something we didn't really see with the Millennium Celebration (also, Journey Into Your Imagination and Millennium Village opened then, which left much to be desired in most people's eyes, which is why they no longer exist). Of course, the Millennium Celebration also brought us the incredible Reflections of Earth and Rock 'n' Roller Coaster...so I can see both arguments...I believe we got Fear Every Drop for the Millennium as well.
So, each celebration saw several great changes, and we can only hope the Tower of Terror will get its best drop sequence yet before this celebration comes to a close. I can understand either argument with one being better than the other, but I don't really get the position that 100 Years is cheap or crappy...we got a lot of new stuff and I haven't heard many complaints about the new parades--except Tapestry of Dreams vs. Tapestry of Nations, but I have heard nothing but raving reviews of Mickey's Jammin' Jungle Parade--my favorite daytime parade.