Another thing that is new is the ability to search within a topic (at least I don't think you could before). This is great if you're looking for something in particular in a very large thread.
That was always true but many members did not know that they could do only a topic (or board) search. But, to do the search, you had to be at the topic or board at the time of the search. It is an improvement, however, to have the pull-down menu to be able to use.
There are many other improvements to the new search engine. It now catches words that it could not catch before, including words with very few letters, and there are more hits in general. Of course, it helps to use enough keywords so that you don't end up with hundreds or even thousands of hits.