The BeBook gets 3 out of 5 due to not supporting the standard formats (mobi,lrf and others) coming soon with the next firmware upgrade.
The iLad gets 3 out of 5 due to being a bit bulky and more useful to students and educators.
And the Sony 505 gets 4 out of 5 for being light weight and supporting the popular formats.
Then again thats there opinion.
