I am about to do my CEH v6 exam, as I did the course in Sept 2010. Leaving it until last minute aren't I!
Anyway, Had i thought about it a little more back in September, I would have waited until v7.
A LOT of the tools in v6 were outdated, to the point where we just skipped over chunks of it.
The wireless security was really outdated too. It mainly talked about WEP security, which I thought was a bit of a waste, as I was hoping to see some good methods and countermeasures for WPA.
They touched on bluetooth hacking which I thought would have been really valuable.
The virtual machines we used all had win2000 vms, and I would have like to see machines running xp, server 2003 at least.
There was sweet bugger all to do with Windows 7, server 2008 or Vista, and nowhere near as much Linux stuff as I expected there would be.
My advice would be to keep the study book, but get the one for v7 (if you haven't paid for the v6 course), then jump straight into the v7 course, you'll be better for it with the newer tools, methods and all around information that will be more relevant to environments more commonly in use today.