Suggest will show the user the most popular search terms based on the amount of text he/she managed to input. The longer the search strich, the more accurate the suggestions become. According to Google, there are at least 3 ways this feature can improve the search experience:
– Help formulate queries: Instead of just typing [hotels in washington] – did you want [hotels in washington dc] or [hotels in washington state]? Don’t remember that song title or person’s name? Let Google help you search (and yes, I ended up choosing "From This Moment" as our wedding song).
– Reduce spelling errors: Since suggestions are spell-corrected using the same "Did you mean?" feature that offers alternative spellings for your query after you search, misspellings and typos can be corrected ahead of time. Instead of wasting your time with a misspelled query like [new yrok times] or [tomorow never dies], search the first time with the correctly-spelled query.
– Saves keystrokes: Who wants to spend their time typing [san francisco chronicle] when you can just type in "san f…" and choose the suggestion right away?
On the other hand, the same feature can turn into a headache for those used to the auto complete feature. They know what they’re looking for, they know they’ve searched for that item previously and thus, are used to type only one or two letters and then get the entire search string. For them, the only Google-Suggest feature that could present some importance is the “turn it off” button.