I grew up on Black Sabbath, used to really enjoy them. I'd say that Tony is such an underrated guitarist, except that "underrated" gets used so much, it doesn't mean anything anymore, so I'll just say he's great and most people don't realize it.
For some reason, Heaven and Hell, the album, doesn't work for me as well as it should. I love Dio's voice, and the songs are good, but it just doesn't gel for me. Sadly, I'm so sick of Ozzy's voice from all the dreck he's released in later years, that I have trouble listening to the older stuff, too.
I'll still crank them up when they come on the radio, though, if that counts for anything.