I must chime in as well...
I had purchased the 505, but returned it in favor of the 700. I read quite a bit in dim/dark conditions, so the lighting is very important to me & I really abhor the idea of needing to have a supply of batteries, or recharging nicads. I really have no problem with the readability.
And as far as the dictionary & annotation...I'm not a student, nor do I read anything other than for pleasure. So those features don't really seem important to me either.
Finally, I'm a real 'Cheap Charlie', and although the idea of being able to wirelessly download books is appealing, there is just so much available free that the extra $ for the new reader doesn't seem worth it, considering I would probably never use that feature.
So, there's my biased opinion, and my unconditional

!!!!