Im my personal experience, Nokia phone, going back to when I had my first one about 7 years ago, have always been among the best in terms of call quality, despite the fact that judging call quality is very superficial (dependant on network, signal and event time of day) but it seems Nokia puts good quality mics and earpieces in their handsets. This 1520 should in theory be the best they have made. Im not sure if those 4 audio recording mics also aid phone calls ?
Even so, I don't much care for Technobuffalo, nor pretty any other mobile review critics out there. They are biased, unfair and not trustworthy, they either nit-pick or simply ignore things that are obviously wrong with a phone (depending on which manufacture are giving them submission I guess). Mobile tech review with Lisa is the best. She did a review of the 1520 and she rated it really high.