I think OFFLINE searching is really important, not every country in the world got internet 3G connection at affordable price. The scenario is like:

Going oversea and got lost in a city and cannot find the way around because of the language barrier. Pull out the N900 and do a search for Hotel and place to go or to get back without needing internet connection or simcard change.

I think this is very handy. Voice turn by turn also very useful when driving in the above scenario.