I think Barnaby was a very solid investigator, and maybe the only TV detective to have his own in-office Forensics Lab, which he operated himself.

But that show went into a tailspin in the later seasons when they brought in J.R. to appeal to the youngins and do some running around and athletic moves that Buddy Ebsen (Jed from The Beverly Hillbillies and the original Tin Man from The Wizard of Oz! *) was getting too old to pull off (although he did retain a surprising amount of athleticism, probably because he had a lean, trained dancer's body). But Mark Shera as J.R. might be the single worst actor I've ever seen in a starring part on TV. He's a charisma black hole and seemed less believable than the gang in Scooby-Doo's Mystery Team.

(*Note: Ebsen was originally cast as The Tin Man, but had to be replaced almost immediately by Jack Haley, because Buddy got very sick from breathing the aluminum dust in the character's metallic makeup.)