I can understand Sonys apprehension for not including a light. Look at what happened with the NST, it has and still has major issues with light holes, the kobo and kindle have also had issues with it. Far as I am concerned until the technology is as least 90% stable and there are way fewer complaints about light tears, Sony made the right decision. I am also one of those readers who rarely if ever have a situation were light is not available. I kind of like to read by a lamp at night on a cushy chair or couch. Don't like to read in bed with my girlfriend sleeping next to me or even when I am by myself. So I am good without a light for now. Though I can see some people who may need it if they like the ease of not having to set up an external light source when they are camping etc. or like to read when their significant other is right next to them.
Anyhoo, I just hope that Sony has something different to offer in the software. The aesthetic of the unit has changed a bit. They got rid of the ridiculous curved bottom.(that right there alone makes it more appealing to me.) And the bezel thickness looks a little more uniform. About the only thing I think they got wrong aesthically speaking are the buttoms again. I like the ones from the T1 and x50 series much better.
Also the light cover they have chosen...(I am not 100% sure about this)...but it looks similar to a light cover that is available for the kobo mini, Roka and one that Gecko made for the T1. You can see them on youtube heres the gecko.
http://www.youtube.com/watch?v=_WMl7js3Kos and Seems to evenly light the face of the reader. So for those rare situations someone may need light I think it will work in a pinch. Plus I kind of like the soft glow of a a good cover lamp as opposed to a blusish glow or whitish reader with a built in light. So its totally a personal preference with the reader of course.
So again I think its mostly going to come down to the software changes for many (especially Sony fans) Maybe more font choices for the font obsessed, more options for spacing, margins, letter size etc. etc. We shall soon find out.