You might want to look for reviews of specific titles that interest you at:
SA-CD.net - Recent Additions
However, I do not vouch for the accuracy of anything stated there.
Some SACDs are multichannel. Usually, with classical titles, this is done such that one does not tend to notice the sound coming from the rear, as (usually) they are trying to accurately recreate the sound you would hear at a concert. Thus, the sound from the rear represents reflected sounds from the back of the auditorium. In my experience, this works extremely well, sounding more real than any two channel recording, assuming one has a good system correctly set up.
Some multichannel titles are done with putting different musicians into different channels. The idea is to put you in the middle of the band, but it is very unnatural for what it would be like to attend a live concert. I have never encountered any classical titles this way; I believe it is most common in popular music, but popular music need not be done this way.
Typically, they remaster the sound better than before, so that SACDs often sound better than earlier releases. But, of course, someone may prefer an earlier remastering, and one may buy a disc that is not typical in any event.
Some SACDs are two channel only. I have one SACD that is mono (though it is put on the disc as if it were stereo, the same as it is done when a mono recording is put on a CD; that is, it is put on the same for the right and left channels of a stereo formated disc).
There are other places you can buy SACDs, including Amazon and many other places that sell CDs online.
