I live in Japan and have been purchasing many of the reissues using the new material and called by different names by the various record labels. DG calls them SHM-CD [super high mastered-CD].
I have read many of the negative comments here about the sound quality and expense of these reissues and some of it, quite frankly, is misguided. First, the sound using the new material is certainly better. If you can't here the difference it is most likely because your stereo rig is itself incapable of distinguishing the sound from the ordinary CD material. It puzzles me why anyone would consider paying the high price asked for the SHM-CDs if he doesn't have a comparably priced stereo system. My stereo is comparable priced: about $70,000 the last time I checked if I had to replace it. I'm not suggesting you need to spend this kind of money to hear the difference, but if you have a system that is under, let's say, $10,000, you might be wasting your money purchasing the new CDs.
What is the difference in the sound? Right away I noticed a qualitative leap in the sound. The difference is at least as great as going from regular encoded CD to a HYBRID SACD. First I thought there was just a jump in bass response, but I soon noticed that the sound across the entire audio spectrum is more easily present. There's a solidarity, ease and presence to the sound that I have never experienced with any regular CD, or for the matter with the Linn Lp turntable I used to have. It is, in short, a VERY satisfying improvement in the sound that gives the listener the impression that he is in the room with the performers.
As for price, yes, the price is really high. I don't know how much this can be accounted for by the amount of research that went into developing the new material or how much the record companies are using the price to make up for loses they have experienced. Perhaps if there are enough people buying the new CDs the price will come down.
I do have one gripe and this is especially directed at DG. They are not remastering the sound using the latest possible bit/word length [24bit/192kHz] before stamping the material. Shame on them!!! It does make a huge difference. For example, I have a copy of of the DG Japanese 24bit mastered Bernstein Beethoven 9th. The sound is much more present than the regular CD. I also have the complete Beethoven Bernstein DG cycle in the new material. The sound, while much improved, does not have quite the clarity of the 24bit reissue. Other labels are using 24bit remastered material. Try the Brahms German Requiem with Klemperer [HQ and 24bit]and you will see what is truly possible when everything that is now technologically possible is being done, that is, of course, if your stereo system is of sufficient quality to take advantage of the new software.
One last word for now. Don't be fooled by those who claim that high end audio is all a scam. I have been refining my audio system since before the days of stereo, always listening before purchasing and have found that everything, even cables and such, make a hugh difference. Since no combination of components renders a perfect copy of a live experience, careful attention must be paid to which components are synergetic. For example, there's a company called The Cable Company which will give you specific recommendations based on knowing the components in your system. My experiences with them during the last decade has been that they are spot on with their suggestions.