What else makes Platinum better, again, besides
I know there's that Plaza thing, but is that it? I'm not trying to be sarcastic here, I want to know.
Well, of course! "Wormier Giratina" just understates the whole thing. He's much more than "wormier," IMO. Then, instead of getting a big fat nothing for fighting your way to the resort area, you get your own house. There's the improved graphics and effects all over the place, not just in the "effed up 3-D dimension." For example, the Elite Four member's rooms all now reflect their preferred Pokemon type. Numerous small inprovements have been made; surfing is much faster, and moves look better and are quicker (the battles feel less choppy as a result). Also, 59 more Pokemon have been added to the Sinnoh Dex, the gym leaders have been improved, the Battle Frontier makes its return ("meh" for me, but a lot of people have been clamoring for that since it was announced), and there's even a cafe in the survival area (another area that was rather skimpy on the features) where you can battle the gym leaders and your rival at higher levels.
You may notice I didn't bring up your point about Shaymin. That's because Skymin looks to me like a starved chihuahua with mold growing on its head and ears. :P Not a "pro" in my book.
Yeah, I'm happy with Platinum.