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. 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 using the O2 network. The fluctuating signal strength problem has affected me since I brought home my new iPhone 3GS.
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. In one case an iPod touch garnered download speeds of 4579ms and uploads of 1363ms, while the iPhone 3GS showed only 1360ms down and 160ms up.
Both problems seem to be more acute using an Airport Extreme/Time Capsule network than a third party solution. For one user, running the same speed test, a Netgear router provided twice the transfer speed and half the latency of an Airport Extreme.
Apple has addressed some user complaints with replacement units. This, however, hasn't solved the problem, even after one person replaced his phone three times. A non-verifiable source has suggested that this has not been corrected in the beta builds of the upcoming 3.1 software.
Most widely reported is the difference in transfer speeds between the 3G and the 3GS.
Michael Krasner has been following this and uploading movies documenting the differences. In his video he is using AT&T DSL in Florida and his Airport Extreme's radio mode is set to 802.11n (802.11b/g compatible) with two Airport Express' extending his network.
Have any of you new iPhone3GS owners been experiencing this?