The new Google Instant certainly can save you a lot of time searching, but you'll really start seeing the speed once you familiarise yourself with its shortcuts.
Big tip of the hat to the folks at Fast Company for their eagle eyes.
Google Instant comes with three starter shortcuts baked in (and here's hoping for even more to follow):
1) Tab to Autocomplete 2) Up and Down keys for suggestion navigation 3) Right arrow key for I'm Feeling Lucky
Again, this time with detail:
To accept Google's autocomplete text prediction while you're typing, just press Tab. For example, if I type 'lifeh', Google Instant suggests Lifehacker. If I press Tab, it'll autocomplete that text so I don't have to finish typing it out. You can then continue typing — and continue accepting suggestions — in the same way as you continue to fill out your query. This isn't necessarily that impressive when you already know the specific word you want to type, but when it starts autocompleting full queries (or even words you're not sure how to spell) and giving the results for those queries, it's pretty convenient.
Next, you can navigate the autocomplete results using your up and down keys. The results below will automatically update to reflect the results for the currently highlighted query.
Finally, If you're already arrowing through the autocomplete options and you see a top result you like, pressing the right arrow key will perform an I'm Feeling Lucky search — which, essentially, will open the top search result for the query you're already looking at.