I bought this set based on the majority of the reviews here that said the picture quality, especially over the original case films was much improved over the DVD versions, and having watched movies 1 - 4 so far I cannot argue with that assessment, they are indeed a lot sharper and much clearer. This will be immediately obvious in the very first scene of the very first movie with the three Klingon ships approaching the VEGER cloud, a massive difference. However there are some oddities in this first film, the first is when Kirk is being given a tour around the refitted Enterprise in the shuttle, as the shuttle pulls out in front of the gantry a part of the cloud on the planet below passes in front of the gantry! It catches your eye the first time making you uncertain what you saw. Next, when he is going under the saucer section and the screen switches to a view up to the underside there are some very large and obvious dirt marks on the camera, at least three that I counted. Finally, when Aylia is walking down into the VEGER pit it is really grainy, so it looks like this scene could not be made better. In the end none these things really matter to me, they are a minor and fleeting annoyance as the set is well worth having purely for the better quality.
The box is nice but way to overpowering in size for my liking so I have made a custom 10-DVD case to hold these films and put the box away in the attic saving space on the shelves and looking better (in my opinion) in the bargain. The cases as individual films though would look really nice together on a shelf if you, like me, do not want to use the box.
None of the films are the special or extended editions, not really a bad thing as the specials and extended versions did not really have a lot more in them, certainly not enough to make owning these a bad thing.
The four movies with forced stream subtitles work perfectly and are all automatically switched on, at least on my Panasonic. This is an important point as on the same machine one of the DVD's did not do this and I had to select it manually when I wanted to watch the film.
On my Onkyo AV Receiver I am getting something called Dolby EX 5.1 Surround (connected via HDMI) which I have never seen before. The sound is crisp and clear, bass is superb and not overpowering, a vast improvement over the original DVD's in every way.