For v8 or thereabouts, I spent some time fixing some fundamental bugs in db and found that it was arcane but remarkably powerful. Since it was lower level, it avoided the endemic debugging problem of misleading you about your program: All it could do was tell you what the machine was doing. (Cdb, sdb, and adb were, at least in my experience, always lying to you.) I may be the only person who appreciated db fully. Once the bugs were gone you really could use it to good effect, as long as you understood the CPU.
But it was buggy and arcane, no question about that.
-rob