I don't like how they claim "performance improvements" meanwhile they're phasing older devices out of the updates claiming that the older hardware can't handle it, even though the performance is somehow "improved."
If the performance is improved from the last version then every device that could handle the last version can handle the version with improved performance. That's how it works. My iPod touch 4th gen (only 1 gen off from the latest. ONE.) has been excluded from iOS 7 because apparently the hardware can't handle it, even though iOS 7 claimed to have increased performance.