I tried it when I was a bairn.. about seven-eight years old.
Needless to say, I didn't catch squat!
There's definitely a technique to it, though.
From what I've heard, it's best to stand with the bow pointing directly downwards (err... spread your legs or you'll get a mighty sore foot) so that you don't miss due to refraction. I expect that a lot of experience fishing with a bow or harpoon could lend you the ability to judge the refraction relatively accurately, though.
I must be missing something though, because I've never been standing in the water and just had a fish swim around my feet... maybe you could bait your shoes I'd like to try it once I get back into archery...
All will rise again for a better day; earth, green, with waterfalls where eagles hunt their prey