The best thing? That the previously searched items may be saved on your computer (or internet browser). In my case, everything is still there!
This. More than once since Instant arrived I've seen an intriguing result go past while I'm typing, but been unable to get back to it. It's OK for routine lookups I do regularly, like seeing what movies are playing; but for investigative, knowledge acquisition type searches I'm finding it more of a distraction than anything else - especially on multiple words, where it feels biased towards the later ones rather than weighting all terms evenly.