Searching just go better!
You can now use advanced search features, such as searching for phrases, excluding keywords, etc.
For example you can write Google Reader to find articles containing both words. If you want to find articles having any of those words, use the OR operator (|) between the keywords (Google | Reader). You can exclude keywords by adding minus (-) sign before them (Google -Reader). You can also search for phrases by wrapping them in double quotes ("Google Reader").
Please note that search results are always ordered by first by relevance, then by date (newest first).
The new search engine is also significantly faster and you should notice it immediately after typing something in the search box.