I recently scored a free 1974 Deelite Apollo 10 speed. As far as I can tell, it has all original parts, but most of the stickers have faded out and there are a few places where the paint has failed completely on the tubes.
As a project bike, would you consider stripping and painting the frame, or simply replace what needs done (tires, bar tape) and ride it as is?
I like old mountain bikes and more modern bikes with thicker tires. I find it improves the riding experience a good bit. Regardless, the bike you have, and ride, is the best bike
The brakes are probably worse, depending on the bike and how nice a bike you'd compare it to could be quite a bit worse. If you're just riding casually and have foresight it's not going to make or break it though.
Oh, and modern shifters are a lot easier, but again not going to be life changing unless you're riding a ton, especially on uneven terrain