Mainly it's bug-free. It doesn't break up large paragraphs and leave 3 lines on one page and then continue the same paragraph on. It never splits quotes away from the word even if the word following the quote isn't within the same style tag as the word (that bug on the Kobo is really starting to annoy me, I see it that often).
The page layouts are very nice also. It has 3 tabs for Home, Applications and Settings.
Home tab has 4 of your most recent books, and access to your complete library. Below that I have mine set for Author List, Collections, and More. All of those are configurable with PRS+ (I think the original 3 were Periodicals, Collections and Notes).
Applications are Pictures (you can load as many as you like and use for sleep screens), Handwriting (take notes on the fly just using your finger or the stylus within the reader), Dictionaries and Text Memos. I really miss not being able to jot down quick notes on the Kobo Glo.
While reading, there's very little wasted space. There's no top margin (unless you set one in your book), and the bottom is a tiny 3/16" wide black bar that shows the page numbers, battery life and time. Double tap a word and the definition instantly pops up. If you bookmark a page, you can add a note. When you bring up the list of your notes and bookmarks, it references the notes by a line of the text and the page number, so it's easy to find what note you want (notes on the Kobo are just annoying to use compared to the Sony).
You can see an image of the Home page here:
http://www.the-ebook-reader.com/images/sony-prs-650.jpg
And like I said, it all just works and works well.
Edit: And when asleep, you can set it for full screen image only of your book cover or add text over the image or text only or use any image you like for the sleep screen, you have total control over your choice. When fully powered off, it's a blank screen you can set to white or black.
And page turns, the infrared just seems much more sensitive and responsive and fast on the Sony. The slightest thumb movement flips the page, and just one page. It's actually faster than the Glo on turning pages even though it's over 2.5 years old. Especially when you figure in the delay before the page flips on the Glo and that it often takes up to 4 swipes to turn the page.