There's no denying that Google Analytics is an extremely useful and powerful set of software. Combined with its price tag (zero), it is one of the most valuable tools in the arsenal of any SEO, webmaster, or internet marketer.
The good news about Google Instant is that it will have no effect on Google Analytics. Query strings will be passed from the search engine to site owners' Analytics accounts without any adjustments necessary. It's a seamless transition.
Google Analytics is without question one of the best free tools available for any website owner. I'm in there every day taking a look at search visitors, goal conversions, funnels, and everything else that can give an insight on the overall trends of traffic and search visibility.