Again this is only anecdotal-level evidence, but I find the same with my devices, battery life improves over several charges. At most of the other forums I frequent (Mobile-review, symbian-freak etc) others report the same.
sounds like I'm too late but here's my two cents worth anyway. Both the sony and the ipod come with average headphones. If you plug a good set of headphones into each of them you will clearly hear that the sound quality on the sony is superior to the ipod.