Artwork has been getting bandied about on the blogs, so I figured I'd put my two cents in. I really prefer books with good artwork and layout. Unfortunately, most old-school publishers can't afford a lot of great art. And then some like to ape the art from the 70's, which I think is a big mistake. This is one area that I think The Haunted Chateau was right about, as it used more modern art, even though the adventure was very old school. I think more publishers should do this. While a Mullen cover is amazing, much of what is used in the interiors is not so amazing. I am aware that great art costs money, though, and the OSR has a limited customer base, so I am willing to accept this. Maybe if I ever hit the lottery, I'll get something published chock-full of great art.
The other issue I have is editing and layout. Most OSR books have decent layouts, so I am pretty happy about that. Editing is up and down though. Some products are extremely well edited, others have one or more typos or missing words on almost every page. This is an area that is extremely important, and many OSR publishers are well aware of it. Some still need help. I hope things continue to improve on both fronts, as has been happening over the last year.