According to TUAW's David Winograd, many iPhone 3GS owners "have reported slow and inconsistent data speeds, along with widely varying amounts of signal strength, when using Wi-Fi."
"Users note that signal strength can fluctuate between one and full bars even when standing right next to the router or when a computer nearby shows a constant signal," Winograd writes. "This goes along with a commensurate reduction in speed. Even at full signal on both the computer and the 3GS, one user reports getting a maximum of 3Mbit downloads on the iPhone while getting nearly 7Mbit downloads on a MacBook."
"The other, more widely reported problem is a sizable speed decrease in the iPhone 3GS as compared to the iPod touch and iPhone 3G tested under the same conditions," Winograd adds.