Old Girlfriend had a mid '70s version - Mustang II. Underpowered and overheated a lot. A real POS but better than a Vega which I guess is a good thing.
Bought a '70 Mach 1 for $500.00. Plenty of go fast, I thought...until I replaced it with a '69 GTO.
Drove a friend's '65 3-speed from NYC to New Hampshire. The car was brought back to Showroom-New condition by a noted restorer. The clutch action was like a wall switch - either on or off. The car was one of the worst-handling things I've EVER driven (and I've been behind the wheel of many real "interesting" cars).
The best thing about the '65 was its looks. Too bad it couldn't get out of its own way and behaved like a Bass Boat around corners. I've seen the "new" Mustang and if they have done a good enough job on the performance, I'll pony up and get one - past experiences be damned.
You'd have liked the one I drove in High School. 56 T-Bird, 68 GTO Judge engine and tranny.