I went cross country on the Northern Tier with an iPad and loved it. I wrote a blog entry, complete with pictures imported from my camera, each night in my tent and uploaded it the next day whenever I found WiFi. My extended stays in Glacier and North Cascades NPs were the only times I couldn't find free Wifi for the uploads.

For me, the iPad was a good balance of usability, durability and power requirements. I got ALL of the power I needed for the iPad, my camera and phone from my hub generator.

That said, you've ultimately got to decide what matters the most to you... there's no universally correct answer to your question.

If interested, here's the blog (keep in mind that it was written entirely on an iPad in a tent!):