Official Google apps for Windows Phone are quite rare but Google Search is one of the few and it just got some improvements. The app lets you search and browse the Web and this update only refines the search capabilities.
Under WP8, Google Search can display your voice commands and as of the latest update, the app has enhanced Google Image viewing. Signed in on your Google account you have the option to sync your search history to other devices. But it’s not a two way street, so you can only sync the search data to other devices and not the other way around.
You can get the app from here. For now, it looks like Google is not very interested to develop more Windows Phone apps but here’s hoping they will change their mind very soon.