I tried Logos on my friends' iPod today and found that it's not very usable, though fast and crisp display and so on.
I think iPad will be much better - others have discussed this in http://community.logos.com/forums/t/24393.aspx
But what else is iPad useful for? Kindle? (it's also reading like Logos) What else do you use it for? What functions from the ordinary PC/Mac you have transferred to iPad in your daily life?