Joyce Van Patten does a good job as Ruth Lytton, but "Old Fashioned Murder" suffers from the producers' tendencies to cast the killer in a sympathetic light. It's clear from seeing her with her mother and family that Ruth gives them a lot for very little return. She's acting to protect her museum and to try to get back some of what has been taken from her...so the cat-and-mouse game with Columbo suffers as a result.
Ruth is certainly crafty (certainly the murder plan she comes up with is inspired), but I never got the feeling she was malicious, and it's that quality that makes so many of the other murderers on the series a joy to watch. They're playing for bigger stakes, and their comeuppance is so much better to watch. When you even see Columbo feel a twinge of sympathy for Ruth at the end, it can't rival the endings of classic episodes like "Suitable for Framing," "Exercise in Fatality," or "Stitch in Crime."
I am still of the opinion that the original run of "Columbo" on the NBC Mystery Movie is far-and-away the best mystery series ever to air, and while I don't believe there are any episodes that are "bad," there are definitely some that are weaker than others. "Old Fashioned Murder" falls into that camp.