What are the "pros and cons" of the iPhone 3GS and iPhone 3G? Which one is right for my needs?

Please note that the iPhone 3G and iPhone 3GS both have been discontinued. However, this Q&A can be quite useful for anyone considering buying or selling either vintage model on the used market.

These days, just about everyone should buy a newer iPhone. The iPhone 3G and iPhone 3GS do not have modern software support and may not even be supported by a phone carrier in your area.

Nevertheless, you can evaluate the pros and cons from the time these models were recent.

Photo Credit: Apple, Inc. (Left - iPhone 3G, Right - iPhone 3GS)

This "run down" may be helpful in making a decision:

Pros (All Models):

• Thin, sleek design.
• Bright, high-resolution display designed for video playback.
• Slick "multi-touch" interface, "self switching" accelerometer, "proximity sensors", and ambient light sensor.
• Large storage capacity for a mobile phone (8 or 16 GB for iPhone 3G, 8, 16 or 32 GB for iPhone 3GS).
• Built-in support for 3G, wi-fi, and Bluetooth 2.0+EDR (2.1+EDR for iPhone 3GS).
• GPS support.
• High-quality pre-installed applications, including a "desktop class" web browser, HTML capable e-mail client, and integrated Google Maps, as well as the potential for thousands of third-party applications via the AppStore.
• Support to read, but not edit, Microsoft Word, Excel, and PowerPoint as well as Adobe PDF files.
• Built-in camera for basic photography (2 megapixels for iPhone 3G, 3 megapixels and video support for iPhone 3GS).
• Inexpensive (but tied to a contract in many countries).

Additional Pros (iPhone 3GS over iPhone 3G):

• Full support for iOS 4.
• Significantly faster than the iPhone 3G (particularly graphics performance -- Open GL ES 2.0 -- which can make a big difference for gaming).
• Improved camera (except for low light performance), with autofocus, macro, and white balance support, and a "tap to focus" feature.
• Video recording support (VGA at 30 FPS, basic "video editing" -- cut the beginning and end of a clip "in camera").
• Support for faster 3G support (7.2 Mbps HSDPA).
• As originally shipped, twice the storage (16 GB or 32 GB rather than 8 GB or 16 GB).
• Modestly better battery life.
• "Oleophobic" oil repellent display.
• Digital compass (particularly useful for orientation on Google Maps).
• VoiceOver & voice control.
• Integrated Nike + iPod support.

Cons (All Models):

• Originally tied to expensive multi-year contracts in many countries.
• No support to edit Microsoft Word, Excel, or PowerPoint files (online editing forthcoming).
• No support for Flash.
• Lack of tactile feedback may bother some users.
• Battery life may be insufficient for heavy users.
• Some competitive mobile phones offer superior cameras and additional features.
• Substantially larger capacity iPod models are available for less money per GB.

Ultimately, if you need an extremely inexpensive smartphone, and you can make do without recent iOS support or app support and your carrier still supports it, the iPhone 3G and iPhone 3GS might work for you. However, the vast majority of users would be better served by a newer model.