CNET UK's review:
HTC Magic Full Review, Mobile Phone Reviews on CNET UK
They say that battery life is good!
"2.5 days out of the battery with medium usage, making calls, surfing the Web and emailing." I found it interesting that they didn't mention any of the 3rd party apps or the marketplace. Maybe if you avoid the 3rd party apps, the battery life is decent?
Overall- If you hate Apple, this is the phone for you.