Instagram for iPhone just hit version 2.5, which marks the first time the app has been updated since Facebook agreed to acquire it back in April. Instagram 2.5 is mostly a visual update, featuring a new Explore tab for browsing hashtags and usernames, search autocomplete, and a revamped profile. In a few moments of using the app, loading pictures and comments appears to be far speedier than before. Opening the camera is also lightning quick, but perhaps what you'll notice the most is the new "Explore" tab, which replaces the Popular tab of yore. Explore has received a new navigational icon, as well as a search bar at the top of the screen for finding other users and hashtags. Previously, the increasingly popular search field was hidden inside a menu.

Instagram 2.5 also features likes (hearts) that optionally post directly to Facebook's Open Graph, in accordance with a new "Like" action Facebook announced last week. A new Settings panel lets you decide whether you want to share all in-app likes to Facebook's News Ticker and Timeline. If you manage a brand Page, you can even post Likes to your brand page from within Instagram. No word about when Instagram's Android app will be updated to maintain parity with its iPhone brother, but we'd assume it's already in the pipes.

Hot tip, via Facebook designer Keegan Jones: long press the camera button to access your camera roll.

Here's the full change log: