Were you able to finish the book and is it as biased as some of the exiled Iranians feared? I can't imagine an academic historian like mr. Cooper not paying a fair share of attention towards the atrocities of the regime. Though he might want to explain the reasons for it from a new perspective perhaps.
I have not been able to finish it yet but I can explain my take on the allegations of bias. Cooper's Main thesis is pretty much the same as James Buchan's
Days of God which makes the same case as
Fall of Heaven but was far more critical of Mohammed Reza and the Pahlavi clan (see also Christopher de Ballingue[sic]
Patroit of Persia a bio of Mossadegh which is also very critical of MR and the Pahlavi's). However, as far as I can tell
Days of God seems to have been more well received as Buchan was making no attempt to defend MR, but also is in the end more critical of Irans political elites and their fecklessness, first with regards to Mossadegh's recklessness, than with the Shah's unwillingness to really smack down on critics and finally on Khomeni's hypocrisy, megalomania, and bloodlust, along with the Iranian tendency to blame outsiders for problems of their own making.
Cooper is more sympathetic to the Shah and the Shabounu (he isn't keen on the dynasty as a whole and sees them as a major factor in undermining MR's standing with the Iranian people); but is still willing to point out their failings and mistakes while drawing attention to how demonising MR is a major cornerstone of the Isalmic republics legitimacy and serves to shut down discussion of Khomeni's atrocities which are far worse.
The main allegation of bias is to some extent justified as Cooper was able to do something that a lot of Iranian scholars couldn't do and that was secure interviews and access to Farah and CP Reza. Other, more prominent Iranian emigre scholars haven't been able to do this (Abbas Milani, Gholam Reza), so jealousy is certainly a factor on their part. However, Cooper is hyperbolic about Farah - at one point called her the most influential female monarch since Catherine II of Russia, which does strain credibility, and does not go into any of the rumors around her sex life (i.e. Constantine II) although he does discuss the Shahs chaotic love life with admirable detachment; and it's refreshing to have Soraya called out for the lazy, surly and immature brat she was for once (ditto Fawzia).
Also embarrassment. A lot of Iranian leftists and Liberians in exile sided with Khomeni prior to the revolution. Since the Shah had shut down constitional channels of criticism and opposition, The main channel of opposition was the mosque and the bazaar. This was mainly due to the fact that in the context of the Cold War the Tudeh (Iran Communist Party) was far too dangerous to support as opposition so Khomeni came to fill that role - it was a case of my enemy's enemy is my friend and the fact that a lot of the left-liberal opposition thought they could control Khomeni. They were wrong. They bet on the wrong horse and are loath to admit so. Hence they keep flogging said dead horse, or reputation of a dead man as be the case. *
*There were also a lot of reactionary old bazaari's and clerics who opposed the Shahs as well, mostly due to the fact it threatened their wealth and privileged standing. Shia clerics owned a lot of land in Iran and were targets of land reform in the 1960s, and the oil boom undermined the wealth of the bazaari's. Incidentally these two groups were responsible for Irans constitional Revolution of 1906 and were the major force in the overthrow of Mossadegh in 1953. The Shah often spoke of a 'red-black' allinace that would be nothing but trouble - it was a self fulfilling prophesy as this is what happens as he managed to alienate both his traditional supporters and those he was trying to win over.