So I just wrote up a moderately substantial post on the iPad directly in the WordPress app. This post as it happens.
The editor is much improved over my first experiences with it. Granted this is hugely helped by having the Apple keyboard that goes with the new iPad, and discovering that holding shift and using the arrow keys selects text. But it is now possible to write reasonably decent posts on an iPad, and having direct access to any photos on the device helps.
The major deficiency would be a lack of footnotes. As some of my readers may have noticed I have a tendency to insert snark as footnotes so that it doesn't distract from the main flow of a review. I usually manage those by drafting in Word and Copy/Pasting to WordPress, but including those directly in the WordPress editor would be glorious.
Otherwise, for basic edits and quick drafts, the iPad will be ideal for [REDACTED] which is starting in 40 days now.
Oh, speaking of photos have a birdie: