I finished Tied In earlier today, and I'm not quite clear what to think of it, yet.
It's all over the place, not only concerning the quality of the various articles in it, but also with the intended target audience. Some of the articles seem to be targeted at the readers of tie-in novels, while others read like they are meant to be a guide for aspiring tie-in writers. I guess that's one of the main symptoms of something that bothered me a bit about the book: A real common thread is missing in this book.
I also think it would have benefited from a tighter editing, as some points seems to be repeated over and over in different articles. (I don't really have to read multiple references to Max Allan Collins' hard time novelizing a movie based on his original story Road to Perdition when he is talking about this in his article, for example).
Overall worth a look if you're interested in Tie-in writing (especially at the price the eBook is going for at the moment), but it definitely has its weaknesses.