Here are reviews for Kindle 3 handling PDFs.
here is a sony review
Finally, here is a comparison of the two from the same reviewer:
I think that the Kindle 3 is a great device for people who want to download a lot of novels from the Amazon bookstore - I would buy one, if I could justify getting two new readers to myself. For people reading a lot of PDFs or who plan to take out library books, I think the Sony is a better choice. Also, I like that the Sony can handle rtf - I use my reader a lot to go over typed class notes. I also like the look of the Sony reader a lot more than the Kindle, especially the metal case. I think that you would be happy with either one, but I'd go with the Sony (I plan on upgrading my 505 to either the 650 or the 950.) I wouldn't mind having a Kindle as well, but between the two devices for my uses the Sony is a better choice. Also, it comes with 12 dictionaries. I read a lot in foreign languages, so this is a big plus for me.
regarding the landscape view on the Sony vs. the Kindle (as mentioned in the youtube review) I actually like that the Sony duplicates the last sentence, so in my book that's a plus. To each his own.