1script - 4:55 pm on Sep 2, 2010 (gmt 0)
As a user, I'm in love-hate relationship with search suggestions myself. I find it useful only in times when what I'm looking for is the suggestion #1. Otherwise it distracts me and sometimes Firefox starts feeling playful and won't let me complete the sentence with my own words and insert one of the suggestions instead (must be a mouse problem,actually).
But whatever it is, it's a complete traffic killer if you were ranking for very long tail keywords: by the time a user would type everything in, they'd be bombarded with dozens of suggestions and chances are they'll give up and take one instead of what they originally wanted to type in. Or, as my experience tells me, their Web browser would do the honors and pick one for them.
Google (and Bing of course) are not only trying to guess the users intent, they are in very real terms shaping it.