Mainstream(and I use that term very loosely) Asatruar have conflicting Views on Mr. Gundarsson(and most every other author including Snorri Sturlusson), some think he is smart and well informed, others think he is a sham. And the purists tend to think that the only way to REALLY understand the religion is to go out, find manuscripts of the Poetic and Prose eddas(in their origional language and form) and translate them yourselves(yep, that means learning a dead language). Using any book from Llewllyn however is generally frowned upon anyway unless it is something like the idiots guide to the rune poem and possibly the most basic principles of Casting the Runes. However, anyone who does do this sort of thing is told repeatedly NOT to cast for themselves(Look what happened when Baldr foresaw his future) and to remember that Odin the runegiver and the Norns never give anything for free. That last part is just sound advice in general