Just got my cover/light and it is a very well-made accessory. The cover is similar to the stock 505 cover, and is about 1/2" wider. The lighting works great, with a few shadowy striations on the leftmost third of the screen. The rightmost 2/3 is very uniformly lit. It is still very easy to read in the dark and the lighting is not noticeable once you get into a book.
I thought the light cover would be heavier and bulkier than it actually is. It's a little bit thicker/wider/heavier than the stock cover, but still overall light and handy.
It is best to read right through the clear lighting plate in normal light (power switch off), which doesn't affect clarity at all. The front cover folds behind for easy one-handed reading. The entire lighting unit is removable, as shown earlier, and snaps in/out just like the 505 does on the stock cover. Without the light, the new cover is very similar to the stock one (a little bit wider, barely thicker at the hinge, and not noticeably heavier). So, it's easy to just leave the 505 in this cover, and remove the light assembly if you aren't using it for a while.
Some of the halo around the edges is generated by a small lip around the sides of the clear lighting panel, which allows the panel to fit in flush over the screen. It's not a problem while reading. I am a bit concerned about scratching the plastic panel. I hope they sell replacement panels if it tends to get scratched.
Overall, I'm very happy with it. This lighted cover appears to be very well-made and well-designed!
(So now, the gf gets my 3-LEDZ-light for her 500!