The two biggest complaints: battery life and overall cost.
The Wall Street Journal technology columnist Walt Mossberg found that in his testing the 3G has less battery life. Mossberg said that because of the higher demands of using 3G networks, the iPhone's battery drained a lot faster than "in a typical day of use than the battery on the original iPhone."
"In daily use, I found the battery indicator on the new 3G model slipping below 20 percent by early afternoon or midafternoon on some days, and it entirely ran out of juice in one day," Mossberg said in a post on his blog.
"I overcame this problem by learning to use Wi-Fi instead of 3G whenever possible, turning down the screen brightness and even turning off 3G altogether, which the phone permits. This is an especially significant problem because, unlike most other smart phones, the iPhone has a sealed battery that can't be replaced with a spare."
The New York Times tech writer David Pogue concurred and in his own review of the 3G in Wednesday's New York Times, noted that when "the battery needs replacement after a couple of years, you'll still have to pay Apple $86 for a replacement."
Apple initially wowed prospective buyers with a price tag of $199 for the 8-GB model, about half the price of the original iPhone, and the 16-GB model phone will cost $299.Both prices are based on signing a two-year agreement with iPhone carrier AT&T. An upgrade fee is $18. The phone carrier also said that customers have an option to purchase an early upgrade priced at $399 for 8 GB or $499 for 16 GB, which also requires a two-year contract. In addition, AT&T said that in the near future, it will offer a no-commitment option of $599 for 8 GB and $699 for 16 GB.
However, Mossberg points out that the price point isn't much of a bargain.
"Apple's exclusive carrier in the U.S., AT&T Inc., has effectively negated the iPhone's up-front price cut by jacking up its monthly fee for unlimited data use by $10.
"Over the course of the two-year contract you must sign to get the lower hardware prices, that adds $240, overwhelming the $200 savings on the phone itself. If you want text messaging, the cost rises further. With the first iPhone, 200 text messages a month came free. Now, 200 messages will cost $5 a month, or another $120 over the two-year contract," Mossberg wrote.
3G reviewers weren't too crazy about the phone's camera too.
"Apple hasn't done much to improve its 2-megapixel camera," said USA Today tech columnist Edward Baig. "You still can't zoom, shoot video or use a flash. Taking pictures is a tad clumsy."
Baig said that other drawbacks include not being able to shoot video, take advantage of Bluetooth stereo or dial with a voice command, which are common features on rival devices.
"I'm hoping some shortcomings will be addressed by third-party developers," he said.
So, what's the bottom line?
"If you've been waiting to buy an iPhone until it dropped in price, or ran on faster cell networks, you might want to take the plunge, if you can live with the higher service costs and the weaker battery life," Mossberg wrote. "The same goes for those with existing iPhones who love the device but crave faster cellular data speeds. But if you already own an iPhone, and can usually use Wi-Fi for data, you probably should hold off and get the free software upgrade before deciding whether it's worth getting the new hardware.
The New York Times' Pogue agreed.
"The iPhone 3G is a nice upgrade. It more than keeps pace with advancing technology, and new buyers will generally be delighted," he wrote. "But it's not so much better that it turns all those original iPhones into has-beens. Indeed, the really big deal is the iPhone 2.0 software and the App Store, neither of which requires buying a new iPhone. That twist may come as a refreshing surprise to planned-obsolescence conspiracy theorists—and everyone who stood in line last year."
