Widescreen > Foolscreen
That's all you need to know.
My father like Foolscreen at first, too...because the bars got on his nerves.
Then I play A Fistful of Dollars for him in both widescreen and foolscreen (the DVD has both), and when he saw the difference, he immediately changed his mind. There's a scene where Clint Eastwood's character walks up to some guys sitting on a fence, a shootout ensues, and he shoots 4 times. In the foolscreen version, you only see 3 guys on the fence, in widescreen, you see all 4, so it doesn't look like he missed a shot and had to hit one of them twice.