Only his family who were present with him would know if it was an "oh wow" of pain, or an "oh wow" of amazement - wouldn't the difference be obvious in the tone of voice?
If he were expressing pain, I somehow doubt that his sister would have chosen to pass that on to the whole world.
Anyway, as a person who was in life open to the possibility of things never before seen or imagined, I like to think that he was, in death as in life, open to possibility, amazed and ready to explore what lay ahead.
Gordon Phinn has a youtube video about a contact with Jobs, by the way. Take a look and see what you all think:
http://www.youtube.com/watch?v=8zqSK8hEMJc&feature=autoshare