I had a couple cobs back in the day and they were great smoking pipes! Honestly, I'd rate them and meers ahead of briars in terms of being sweet-smoking. They weren't prone to souring and required little or no resting. As I happen to prefer shorter smokes, I found the size pretty much perfect (not counting the MacArthur style which I never owned). The cob itself seemed apt to last forever, never had one burn out on me. It was the stems that gave out. I'm not a clencher and still managed to crack the mouthpieces, and in those days before the internet I don't recall a ready source for replacements, it was easier and probably just as economical to run down to the drugstore and buy a new pipe. Today there are even beefed-up replacements, but they seem to cost more than the pipe by a lot, so I probably wouldn't go for one if I still smoked cobs.
The reason I don't smoke cobs today is purely a personal thing. Corncob pipes evoke for me the image of Popeye and Mammy Yoakum and I grew up in the boonies and am still sensitive about the rube/hick/redneck/hillbilly stigma. I feel embarrassed to smoke one even if nobody sees me with it. I'm ashamed of my snobbery but I just can't seem to get over it. A pity because like I said, I like how they smoke better than briars, I just don't like how they look.