The Main Legendary is Giratina in his worm form.
The Male Trainer will have a new costume, a blue hoody and a white/silverish backpack
Regigigas and Shaymin will both have at least one new form.
The battle interface will now be black.
Giratina will now have an important role in the storyline.
The Underground will now have Wi-Fi capabilities.
There will be a new Battle Frontier-like area called Battle Island
Shaymin will automatically convert to Sky Forme when sent over to Platinum and will stay Land Forme on Diamond & Pearl
The Torn World, positioned above the Spear Pillar, really utilises the 3D engine of the game and has the lands in a 3D isometric view
There are various other new areas positioned in Sinnoh for you to explore
there just gathered a;ll of that
and just a bit more info there may be acces to the regis so thats all for now
Jordan