The iPhone phenomenon has well and truly arrived. Part of the appeal of the popular device is Apple's App Store — an interface allowing users to purchase and download third-party applications developed specifically for use on the iPhone and iPod touch.

One of the most popular applications is Facebook, a mobile version of the popular social networking site. Although Facebook previously offered a special version of the site suited for use on the iPhone's Safari browser, the latest application takes the user experience to a new level. This simple but well-designed application offers fast access to friend updates, profiles and your inbox and even allows you to chat to users who are currently online, though it does leave out plenty of other features.

Like many iPhone apps, Facebook makes use of a menu bar at the bottom of the iPhone screen. There are menus for home, your profile, your friends list, live chat and your message inbox. As soon as you log into the application, your latest friend updates are displayed in a simple list format, which you can scroll through using your finger. From here, pressing a small arrow alongside a friend's update opens their profile, allowing you to read and write on the wall, access mini-feeds, view photos and read personal information.

The interface of this application is excellent. It's particularly easy to update your status on the move, and the absence of advertisements is sure to please many users. You can view and make comments on photos and browse through albums — images are automatically resized when using the built-in accelerometer, which is a great feature. An oversight is the fact that you can't save pictures as caller ID images, which would have been a handy inclusion for iPhone users.

What you can do, however, is take a photo with the iPhone's camera and upload it to your profile in seconds. Unfortunately, tapping a photo in your album uploads it immediately which may mean plenty of photos being accidentally uploaded. In addition, you can't tag users nor write a caption during this process; you can make a comment about the photo once it's been uploaded, however.

Perhaps the best feature is live chat. Using an interface similar to Apple's iChat and the iPhone's threaded SMS application, Facebook's chat function shows a list of currently online friends and a simple tap on their name opens a window for messaging. If you are browsing another area of Facebook and receive a message, an alert notification will appear on the chat icon.

Although Facebook is a reasonable application and it is user friendly, its current limitations mean that it's not a replacement for the full Web version. More support for photos and albums as well as the ability to accept and reject friend requests and view groups and events would be welcome additions. We also experienced a number of crashes during testing; this suggests that stability isn't quite as strong as it should be.