John....
I bought Martin Evening's book. I can't say it's any better or worse than others since it's the only one I've read. Likewise I can't say how useful you would find it because I don't know your background.
For me it didn't really provide much more information than I got from just playing with LR. I didn't come away with any feeling that I could improve on my workflow because my needs I guess were different from Martin's way of working.
You'll find a number of web video tutorials that may be of more help. Here's a link to get you started - there are other sites as well.
http://lightroom-news.com/Colin