DDC Comments: The greatest benefit is that pre-1976 patents are now text-searchable. This is huge for historians, but I suspect that we will now see more citations based on these older documents. Google searches are very fast as compared to other search engines. One problem: Google is best at finding the top-twenty references related to your search. Google is much worse at doing exhaustive searches. Thus, if you want to find every patent that mentions a certain term, you will probably not be successful (at this point) with the Google Patent Search. Finally, Google does not yet have a link to the PDF version of the document.
Please try out the search and leave your own comments below.
Other useful free patent search engines: