I just finished The Caves of Steel. I read it based on a high recommendation from a coworker that said this is the book to start on with Asimov. In the end, I thought it was a horrible book. It's been a long time since I've ready Hardy Boys, but I kept feeling that it was reminiscent of that series. I thought the story was bland. The environment wasn't interesting. The mystery wasn't complicated in any sense. I would have been OK with those things, if only the characters were interesting. If anything, I disliked the characters, but not enough so that it made me connect with them even on a negative level. The one redeeming value I gave the book was that it was short enough that I didn't feel like I lost a significant part of my life by reading it. I probably won't go on to read any more Asimov, but I am still curious because I see comments like "Greatest science fiction of all time" when Asimov comes up.
Asimov wrote a lot. Extremely prolific. A lot of it isn't worth your time, but Foundation is one of the high points. A lot of his work, like Heinlein's, seems dated since he wrote it so early in the technological revolution (that we're still in).