It's interesting how polarizing the opinions on the N64 controllers are. I played the hell out of N64 games when they were current as a teenager, and to this day I still find the N64 controller one of the most comfortable and natural controllers to use. So I wonder if childhood acclimation has anything to do with it. (I feel the same about the Atari 2600/800 standard Joystick, which also has similar polarizing opinion). On the other hand, I never cared for Genesis controllers even though many people preferred them to the alternatives at the time. I didn't get a Genesis until only a year or two ago.
Absolutely agree on the durability (or lack thereof). There's several replacement thumbsticks using Gamecube-style sticks that look like they'd be a nice upgrade. May have to grab a few for mine.
Never had a problem with cooling, and the only cart I have that doesn't work is a Mario Kart 64 that looks like someone left it outside for a year or two.