iPhone 4 - Connectivity and Internal Hardware
Another new internal feature of the iPhone 4 is a three-axis gyroscope, which gives it the ability to detect pitch, roll and yaw. Along with the existing accelerometer this gives it six-axis of motion detection, allowing Wii-mote levels of gesturing to control games and other apps. Sadly we couldn't get hold of any applications that took advantage of this, though expect them to start arriving thick and fast.
Wireless connectivity has also had a boost with 802.11n Wi-Fi and HSUPA to augment the wireless connections on previous models. The faster Wi-Fi is a nice addition, but has few practical uses that we can see beyond it being a slightly more stable and longer range connection. It's main advantage of greater transfer rates is made moot by Apple still not alowing wireless syncing and data transfer.
For all other applications like downloading apps and files, your broadband is more likely to be the limiting factor before your Wi-Fi. As for the HSUPA, again, it's a nice addition but so few network providers support it that you're unlikely to see massive gains. Certainly in our tests, we saw no significant or consistant difference between an iPhone 3G and the iPhone 4 when both on O2.
iPhone 4 - Battery Life
Despite all these hardware improvements, Apple has actually managed to improve battery life with you getting up to 7h 3G talk time, 6h 3G browsing, 10h Wi-Fi browsing, 10h video playback, 40h audio playback and 300h on standby. This compares to the 3GS figures of 5h 3G talk time, 5h 3G browsing, 9h WiFi browsing, 10h video playback, 30h audio playback and 300hrs on standby. We simply haven't had the phone long enough to fully test these claims, but early indications are that it does indeed last that bit longer with a day's intensive using less battery than we would expect. Whether it will stretch to more than a day with anything like extensive use, we're yet to see, though.
iPhone 4 - Performance and A4 Processor
To power all the extra pixels in its screen, Apple has given the iPhone 4 a major speed bump, adding the same A4 processor as used on its iPad. We still can't get any word on whether it actually runs at the same speed (we're assuming it's slower) as the that in the iPad but certainly all the same features, like HD video playback, are there.
The result is a phone that feels noticeably, if not significantly, faster than the 3GS, which itself was a huge improvement over the iPhone 3G and '2G'. It does, however, seem slower than the iPad. In terms of out and out app performance, it's probably no quicker than the latest alternative smartphones that use the 1GHz Qualcomm Snapdragon processor, like the HTC Desire, but the general interface is easily as snappy.
In terms of what the extra power does mean for application performance, it's difficult to tell. The huge catalogue of existing games and apps are of course all programmed to work on the existing iPhones so we've yet to see any app that really pushes the new hardware. Certainly those existing ones we tried did look and feel better and faster. Games in particular really benefited from the combination of the improved screen and performance and provided a much more rewarding and immersive experience.