The new search feature will copy GIFs to your clipboard so you can paste them into messages and can even choose GIFs from what you type for contextual searches. If you type something like "yaaaas!" or something inane like that, you can search for matching GIFs of that nature.
Microsoft is planning on adding in additional themes, support for iOS text replacement and cursor placement using 3D Touch.
The new built-in search is obviously meant to compete with Google, after Google previously released the Gboard keyboard for iPhone with built-in search.
There are several different keyboards available for iPhone to choose from, but now that giants like Microsoft and Google have made their own options available, the vanilla iPhone keyboard seems like an afterthought, especially considering Microsoft previously acquired SwiftKey.
It'll all come down to personal preference, but Microsoft just shot ahead to Google's level with its addition of these new features.