After lots of hype, the new iPhone 3GS has arrived, boasting an improved camera, better battery life, and speedier performance. But is it a must?  The iPhone 3GS is available in two versions: 16GB and 32GB. The 16GB version costs $199, while the 32GB version costs $299. From the outside, the iPhone 3GS looks exactly like the iPhone 3G. Like the iPhone 3G, the new model comes in black and white versions, and sports a 3.5-inch touch screen. Most of the changes to the iPhone 3GS have been made on the inside. Apple says that battery life is better, but the biggest boost is in the iPhone's speed: The iPhone 3GS runs twice as fast as the iPhone 3G. Instead of a lot of software installed on it, the iPhone 3GS comes with the most recent version of the iPhone Software --version 3.0- installed, but it does come with easy access to Apple's App Store. The speedier performance of the iPhone 3GS extends to surfing the Web, too. You can see entire Web pages, and can zoom in and out with ease. The notable new messaging feature on the iPhone 3GS is support for MMS. You can send pictures and videos by SMS, rather than having to send them via e-mail. Other new and very-handy e-mail features include the ability to search through your e-mail messages and contacts, as well as the option to use a landscape-oriented keyboard when composing messages. The camera has been upgraded from 2 megapixels to 3 megapxiels, and adds auto-focus. If you already own an iPhone 3G, the iPhone 3GS may not be worth the additional cost, since you can get many of its cool features for free with the iPhone 3.0 software upgrade. But if you've been using an older iPhone or smart phone, or are new to the smart phone world, the iPhone 3GS will amaze you with its speed and plentiful features. The difference between 3G and 3GS lies mainly in   _  .
their color1s their outside shapes their screens their batteries and speeds