Generally speaking, each of the reviewers concluded that Apple has taken one of the most revolutionary products of modern times and made it even better. Some, however, offer different assessments of the handset's new camera functions, though all agree that new Voice Control features leave much to be desired.
The Wall Street Journal's Walt Mossberg
Speed is the most important feature. Apps launch quicker, webpages load faster, and so does the camera.
Cellular-data speeds were about the same but WiFi speeds improved 30-50%.
The iPhone 3G S's battery never showed signs of running dry before the end of Walt's day, even though he was using it excessively for testing purposes, unlike the iPhone 3G's which would often fall into the red zone.
The new 3-megapixel camera worked well, but Walt doesn't think the pictures it took were dramatically better than those on the iPhone 3G, "and it can't compete with phones like Nokia's new $700 N97, which has a 5-megapixel camera with zoom."
Video recording works well, but the iPhone doesn't take HD movies and its quality pales in comparison to the popular $229 Flip pocket camcorder.
Voice control isn't perfect but works most of the time.
Compass isn't that important but works well and can orient maps in the direction you're heading.
The iPhone 3G crashed twice during Walt's tests: once when using voice control and a second time when downloading a TV show from iTunes mobile.
Find My iPhone, Voice Memos, and Push Notification each worked well, but Wi-Fi Auto-Authentication failed repeatedly.
"Bottom Line: Both the new iPhone and iPhone OS are packed with features that make a great product even better. But, for many users, the software may be enough of a boost to keep them from buying the new model."
USA Today's Edward Baig
"The changes make an already marvelous device that much better."
Voice Control is less than perfect, especially in noisy environments.
The iPhone still doesn't multi-task as well as Palm's new Pre.
Shooting video is "dirt simple," and while it's not HD, the VGA quality of the videos is "quite decent."
However, Ed accidently tapped the Trim button in the on-screen video editor and lost scenes he wanted to keep.
The camera performs well for close-ups in still shots, but there's still no solution for low-light situations.
Spotlight search was cited by Ed as his favorite new feature.
"The 3.0 software and 3G S phone may not check off everything on your iPhone wish list. But they give iPhone loyalists plenty of new reasons to celebrate."
Chicago Sun-Times' Andy Ihnatko
"The 'S' in 3G S does indeed stand for Speed, which is something that this model communicated pretty damned effectively during my first few hours with the machine."
In San Francisco, web page downloads "flowed in so quickly" on the iPhone 3G S that Andy had no need to "find something to do" while pages finished rendering, like is often the case on his iPhone 3G and other smartphones.
"Safari on the iPhone 3G S seems as interactive as a desktop browser."
"Gaming has been kicked up a notch; intensive 3D games are elevated from 'Wow, thats a great frame rate for a phone!' to simply 'Wow.'"
Battery life shows noticeable improvements over the iPhone 3G, though Andy still recommends that power users cary an extra battery pack.
The close-focusing feature of the iPhone 3G S' new 3-megapixel camera is good enough to open the door to "porting some of the coolest Google Android Phone software, such as apps that can image the barcode off of a store item and instantly tell you where you can buy it online for cheaper."
The Camera apps new tap to focus feature stands out amongst all other smartphone camera apps.
The file size of each individual video recording is capped at 2 gigabytes, which translates to about an hours worth of video per clip.
Even though it's "still just a phone camera" the video quality is "impressively smooth and natural" and the sound quality "is practically astonishing when you consider that this microphone was designed to pick up sounds spoken directly into it from three inches away."
Using the new Voice Control app, "nearly every command that involved the name of an artist or song was misinterpreted."
Existing car integration kits also don't work well with Voice Control.
The compass, though currently limited in its use, will inspire many new apps but has already "boosted Google Maps into the Giga-awesome range."
"The new iPhone is more than its individual features. Its a convincing vote of faith. Even if a current 3G owner decides to wait until his or her contract expires so they can buy the next-generation at a good incentive price, theres little chance that theyll switch to anything else in the interim."
The New York Time's David Pogue
"It looks identical to last years iPhone, but its faster circuitry makes a huge difference."
The color and clarity of photos taken by the new 3MP camera "are definitely improved, especially in low light."
Although the video function of the new camera tends to "blow out" the bright areas, the end result is "darned close" to what you'd get from a proper digital camera or a Flip camcorder.
However, the ability to trim photos via the iPhone's touch screen is much better than what you'd find on a digital camera.
In Google Maps, the new compass function delivers an indicator beam, showing which way youre facing on the map. "No longer must you walk in a circle, staring at the iPhone map like an idiot, just to figure out which way is up."
The screens new oleophobic coating "lets you wipe away fingerprints with a single rub on your clothes" and "really works to keep the iPhone looking new longer."
Battery life is about 25% longer than the iPhone 3G.
"All of these changes make it much harder to resist the iPhone on intellectual, feature-counting grounds. The new iPhone doesnt just catch up to its rivals it vaults a year ahead of them."
Wired's Steven Levy
"You don't need a stopwatch to notice the new phone is zippier than its predecessor."
Voice Control did better at figuring out the people Steve want to call rather than the music he wanted to play.
Still, "Voice Control is easier than fumbling through the iPod menus, a difficult task while walking and a dangerous one while driving."
Landscape keyboard mode is available in more apps and "makes Apple's 'soft' keyboard much less prone to constant mistypings."
Voice memos, parental controls, and Safari auto-fill work nicely.
"In short, the 3GS offers a boatload of improvements on the iPhone 3G with no real downside and the same price. Brand-new iPhone customers should have no hesitation before buying: Considering the huge variety of apps, there's no better smartphone to buy today."
For existing iPhone customers, however, Voice Control, the new camera, and the speed boost may not be a huge sacrifice to go without.