I have both the Lucky book and InStyle. I like them both. Lucky shows more options on how to wear things and how to accesorize things. InStyle is more to inform you on how to dress for your body. Like short-waisted, pear-shaped...etc. If you need help on how to dress to complement your body, get InStyle. If you just want some better ideas of how to wear things, get Lucky
Do you mean the new one sponsered by Express? I just got it and it's set up more like the Lucky shopping manual in format, not like the original InStyle book. Portions of it was from past magazine issue features such as One jacket/jeans/blouse/skirt four ways. They used the exact same pictures which was sort of a letdown. There are celebrity pics to illustrate style/porportion if you like that sort of thing.
I would say that it's just okay...I picked mine up on Ebay so it wasn't terribly a waste of money and I collect style books anyway. JMHO, I'd give it about a five on a scale of 1- 10. HIH!
I have both books as well. For both, they were just something I looked through one or two times and then never really re-visited. I don't really use them as a reference or anything. If I needed fashion advice or opinions I'd come here :)