I guess I'm a fortunate individual who does not have a massively large TV or projection screen to view the films on.
I just have a 42" LCD 1080p TV connected to my Denon 1513 AVR which is connected to my speakers and my PS3 for Blu-Ray viewing. So unless there is a really massive issue with a Blu-Ray, I really can't see a great deal of it due to my, compared to many of you folks', large screens. I picked up the Terminator/T2 blu-rays a while back when I saw it in a bin at Target for about $10 total. On my system, the film looked fine to me. (As do the BttF Blu-Rays which I had heard are not of the highest quality).
With the new transfer for the UK disc, I went on the PS3 and took a look at the comparison photos that have been posted all over this thread and was quite stunned by how much "crisper" the new transfer is. Still, on a system of my size the blu-rays that I have are still acceptable for watching a movie when I just want to watch one. Am a proponent of getting the best possible picture/audio quality out there? Yes. I am also a VERY strong proponent of ensuring that original audio tracks are included in a release on Blu-Ray. As I mentioned in the Indiana Jones Trilogy thread, movies are a form of art and how they were originally presented in the theaters should be preserved in order to preserve that art.
While the director/producer/etc. own the films in the legal sense of it, once they are displayed publicly and introduced into society, society then "owns" the movie in the general sense of the term. ANY type of modifications to that movie which permanently remove the original audio/video are akin to doing things such as straightening the Leaning Tower of Pisa, or adding a tan to the Mona Lisa, or knocking down the Pyramids in Egypt and re-building them with modern materials. As long as the original film is preserved, a director/producer/studio/etc. can do whatever the hell they want with them as long as the originals are still available for the general public who now "owns" that work of art.
I like the Star Wars films. I'm not too fond of what Lucas did with all his changes and refusing to release the original, un-altered films, but I'm not going crazy about it and still purchased the Blu-Rays so that I could at least watch the movies. I picked up the Fellowship of the Ring extended edition, and while a lot of people talk about the massive color shift in that movie, it doesn't really negatively impact me. I also picked up the James Bond 50 set a few weeks ago and notice some issues in those films, but nothing that makes me feel like publicly arguing about it.
To sum it up, from what I have seen the new transfer for The Terminator is far cleaner and crisper than the Blu-Ray I currently own. The coloring, however, has definitely been touched. Though some here have tried arguing that Cameron gave his approval on this and therefore that's exactly what he wants, I do have a counterpoint to that. The counterpoint is $$$$$$$$$$$$$$$$$$$. The number one priority of studios is to make money. Preservation of the audio/video is reduced if it will cost them more money. There's a possibility that Cameron didn't really like the audio/video 100% but was told by the studio that if he didn't approve this so they could release the movie by x-date that he wouldn't get nearly as much money. In society today, money talks.