We do know exactly who is Ph.d. Rimantas Zizas - he is a scientific associate of Lithuanian Institute of History , he is also member of "The International Commission for evaluation of the crimes of Nazi and Soviet occupations", so i doubt that allegations on "bias" do apply. 
Also, I do not like seeing books attacked, rather than providing exact citations from reviews - what errors, what authors, what article in the book, criticized for what. General accusations of book being "anti-Polish" or even whole country historiography as biased does not work, it's not evidence, it's WP:POV.