Well, I think it's best to get into specific titles then...
I liked the Dire Straits - s/t, compared it to my old redbook CD, and it's better, more detail, more relaxed too.
The Stevie Wonder titles I got were *very* different from the recent remastered CDs. While the CDs had gobs of top end (to be point of fatigue), the SACDs lack a bit of sparkle. But overall, they're more relaxed, better souding, and most likely more like the original tape (as I find it hard for a 70s recording to have that much treble).
Rainbow - Rising is the proverbial "pig" with the lipstick. It's no better than the CD. Horribly compressed and strident, borderline unlistenable.
The other prog titles I got, Camel, Caravan, Gentle Giant, etc, are all nice, like the Dire Straits above.
Oh, I heard the Steely Dan SHM-SACDs, and I concur with Mark. Any ol' vinyl pressing will be better, more extended and detailed, than the SACD.