Might not be so much about functionality as that it was down an awful lot when it was launched. To the point where several people I know gave up relying on it - a feature that works less than 95% of the time quickly becomes 0% useful because the small fraction of failures is so frustrating and annoying that you avoid the whole thing (until recently this problem applied to speech recognition in general, but it's just finally getting over that hump, I think).