The extended versions have already been published in DVD The Lord of the Rings: Special Extended Edition Trilogy (12 Discs) (Widescreen)
this is a Blu Ray version of this package.
THE improvement of the Blu Ray version is the inclusion of HD versions of the movies. Image and sound are great although there is a buzz regarding the new color timing of the Fellowship. No changes on the bonuses which are in SD but no big deal IMHO.
Packaging is far from being on par with the DVD edition but it is OK. The biggest annoyance is the inclusion of FIVE trailers that you have to skip individually since the direct access to the menu is forbidden. That sucks badly.