I find this book relevant and very informative. If you want to master LINQ lingo, just read it.
For broader evaluation see my review on DZone.
P.S. DZone’s IT Book Zone is another great initiative. In short DZone gives you a free copy of a book and expects to receive its review in return. Fair agreement – one can stretch the envelope of IT domains for free, while DZone broadens thier public resources.