Let me tell you, HSM is absolutely perfect for forgetting that you're nauseated (unless, of course, watching a Disney movie will make you more nauseated :). But if you want to feel like a kid, get a bunch of eye and ear candy, and grin, emotionally ache, and wiggle on cue like an idiot for 2 hours, these are the movies for you. It is joie de vivre, distilled. And not that these movies provide a lot of scope for it, but Zac Efron can actually act.
Did anybody else notice that there's one scene in each of the three movies where his character (Troy Bolton) glances at his wrist as if looking at a watch, but he's not wearing one? It's like some kind of odd little running joke that doesn't get any laughs, just a curious nod. Oh, and I love the scene in HSM 2 where he escapes from an awful dinner party and lets out a feral scream. HSM 2 has more philosophical value, plot development, and character development, both in terms of depth (relatively speaking!) and breadth of characters, than the other two movies, so it's my favorite. Ashley Tisdale also has some acting skill; her caricature of the blond drama queen (Sharpay Evans) is spot-on and is all the more effective when the facade briefly drops in HSM 2. Lucas Grabeel (Ryan Evans) is wonderful, especially in HSM 2 and 3, where he gets to come out from behind Ashley Tisdale's shadow and they dropped the "Ryan-is-dumb" trait that his character had in HSM 1. His work in "I Don't Dance" is so much fun to watch. Likewise, Corbin Bleu was a joy to watch, with his athletic dancing, crazy hair, and solid role as a foil for Troy. He and Monique Coleman get some fun banter and dancing together. Olesya Rulin (Kelsi Nielsen) was sweet and clever: I liked how her singing voice was quiet compared to the others', and her portrayal of a quiet pianist and composer who seemed to be a hopeless romantic was delightful. She's the fairy godmother of the films. I loved that one of the jocks, Zeke, played by Chris Warren Jr., revealed that he loves baking, because it's right up jcobleigh 's alley. When Zeke excitedly shows Troy a crème brûlée and Troy asks what it is, jcobleigh explained it along with Zeke. Lastly (but not least!), KayCee Stroh (Martha Cox) was a wonderful character actress: her smile lights up the screen and her dancing makes me want to dance along.
I really enjoy listening to Vanessa Hudgens sing, and she and Efron have a completely engaging chemistry on screen. I initially found it difficult to believe that her character (Gabriella Montez) is an intellectual giant (something I easily believed of Monique Coleman's character), but after watching all three movies, her performance grew on me as well. Hudgens' character is understated compared to all the rest of them. Gabriella Montez is retiring, quieter, not usually at the front of the party drawing attention to herself with a flashy personality. She's generally only in the center of the action because that's where Troy is, but she's more than capable of striking out on her own when she needs to, and you don't realize what you're missing until she's gone. One of the charms of the Troy / Gabriella relationship (around which the plots of all three movies tend to revolve) is the way that the more socially-outgoing Troy draws Gabriella out and encourages her to shine. Similarly, she motivates him to do the right thing (although not necessarily the easy thing), so an interesting pattern gets set up: he's content with the status quo, she sees more potential in him, he reluctantly rises to the occasion, and since he's a leader amongst his friends, the rest of them rise to the occasion as well, to great success. She's the quiet lever behind pretty much everything in the plot, but she doesn't draw attention to herself.
To summarize, adapting the words of Orson Scott Card: the High School Musical movies are not "good movies" in the pretentious, edgy, wish-for-death Oscar-bait sense. They're good movies in the Frank Capra, aren't-humans-cool, isn't-love-wonderful sense.