I held both the Sony and the Kobo in my hands before purchasing my Kobo, and the glare on that Sony screen was a big factor in my decision. The Kobo screen is very nice, matte and clear and easy to read.
I have the original blue-button Kobo, and I don't find that it's that slow. I wish I could have gotten it for $70! As others have said, one of the main issues with the Kobo is reading PDFs. I absolutely hate it, because it requires turning the book to landscape mode and then clicking down through the page. I avoid PDFs because of this. But EPUBs work great, and as far as I know, that's what the books from the Sony store are, so you should be fine.
Oh, and you can also read library books on the Kobo. I've been doing that lately to save money. It's so nice to be able to go to the library without actually having to physically go there... and you don't even have to worry about overdue fines because the books "return" themselves automatically! Had I known how much use I was going to get out of the library with my Kobo, I might have bought it sooner.
Last edited by La Coccinelle; 03-12-2011 at 04:38 PM.