Why you should—or shouldn't—buy the iPhone 4S

We have the new Apple iPhone 4S in house, and we'll have our first hands-on review later today. In the meantime, we have some advice for anyone who is considering rushing out of the house to wait on line to buy the phone today or later this weekend: Do it. Or don't. Depending on what kind of phone you currently have, and what features are important to you, now may be the time to get a new iPhone. Here are some things to consider:

What's better:

• The iPhone 4S has an advanced speech-recognition program called Siri that lets you give the phone complex commands without touching the screen, which can make it easier to do everything from making routine phone calls to searching the web.
• The phone's new processor is faster—it's reportedly the same one Apple uses in the iPad 2. And that may help enable smoother multitasking, not to mention more fluid movement and greater functionality in games and other processor-intensive apps.
• The phone now has an 8-megapixel camera, compared to 5 megapixels in the iPhone 4. And a new lens promises make it easier to take sharp pictures even in low light.

What's not:

• The phone lacks access to the fastest 4G networks, such as Verizon's LTE network, which puts it at least a half-generation behind some other recent models from other companies.
• Although Apple claims the 4S has better battery life than earlier models, the phone still has a non-removable battery, which limits your ability to add juice if the power starts running low and you're away from a power source.
• The screen is still only 3.5 inches. Many newer phones have 4-inch, and even 4.5-inch screens, and still fit comfortably in a shirt pocket.

So, should you get on line today? If you're a happy iPhone customer, and have been using early models such as the original iPhone or iPhone 3G, chances are you'll find this a worthy upgrade. If you're a satisfied 3GS or iPhone 4 user, you can install iOS 5, and freshen up your phone without having to pay for new hardware (though you won't get Siri, or any of the hardware upgrades, such as the new processor or camera).

If you're on the fence about switching to the iPhone from another platform, you should take a close look at some of the new features and see how important they are to you, and what the trade-offs are. If you're looking for the fastest 4G access, for example, the iPhone 4S probably isn't right for you.