From the other 'instant' clones out there, including youtube instant, and hacker news instant, I would not consider it to be a failure.
Immitation is the sincerest form of flattery.
After all, Youtube instant supposedly had traffic in millions, and the chap was offered a job. Was that a kind of PR ploy? May be. May be not.
However, I would be interested to see how Google instant impacts Google Trends.