The box itself: It feels very sturdy and well put together. The transparent plastic around it might be a little annoying when you have to remove it every time you take a disk out or put one back in, but it protects the box itself from scratches and dirt. Each DVD comes in a plastic slim DVD case.
The films: The film quality is astounding! In comparison to the previously released 'Special Edition' dual DVDs, picture quality has been dramatically improved! It's much clearer and sharper and the colours do not 'bleed'. Also, picture noise has been almost eliminated, so that smoke and close up exterior shots of starships' hulls are perfectly clear and sharp. Plus, compression artefacts are nowhere to be seen. The sound has also been improved, although I still think that 'The Wrath of Kahn' sounds like they used inferiour audio equipment when they recorded the actors' lines... but that's only a personal opinion.
All in all I highly recommend this boxset if you don't own the previous Special Editions or if you want a serious upgrade in picture quality. Then again, you might think of getting them on bluray if you happen to have a player.