Sorry it's taken a few days to provide the examples; I'm rarely at my computer anymore, and referencing things on my phone is a pain. So here we go:
3-Page Preview
First sentence under "Introduction:" capitalization is all over the place.
Bottom of Page 4, last line of left column: extend the campaign beyond what? At least one word is clearly missing here.
Bottom of Page 5, last line of left column: "Appendix" should be capitalized.
Tomb of Horrors Preview:
First page, in the sidebar under Eberron: "among Shargon's Teeth." That's the entirety of the "sentence."
In addition, both previews are rife with run-on sentences and repetitive wording. I don't expect that those issues will ever be resolved, no matter how many printings the book sees, but it still makes me sad. These are issues most of us have weeded out of our writing by the time we graduate from high school.
Don't get me wrong; my own writing is far from perfect, and I don't imagine anybody's is. But it doesn't speak too well of the editing staff of a major company to have so much stuff like this slip through the cracks - my writing isn't perfect, but that's why I have other people look it over before publication. Which means that when my writing does hit the streets, it actually reads better than most of the stuff in these previews. I mean seriously, four issues in five pages? That's a baaaaaad proportion.