Auto-vectorization

So I decided to mess around with the auto-vectorization in gcc and I must say, it sucks balls. I certainly didn't expect it to generate decent code, but I kinda expected to, you know, vectorize easily vectorizable loops? Like

for(i=0; i<512; i++)
    samples[i] *= window[i];

Seriously, it doesn't get much simpler than this. And gcc leaves it as scalar. So, /prog/, is auto-vectorization good for anything now other than marketing fodder?