Depending upon where you were seeing the earliest comments, it may have been more about the render quality than the animation. I went back and checked, and, yeah, the Roxy BJ scene in the shower is a pretty rudimentary low-render animation (only 3 or 4 frames making up the head bobbing); I compared that to the most recent Roxy scene where MC is ass-fucking her in her apartment, and that animation has a much higher number of frames and looks much, much smoother.
So, if someone was writing about something beyond the first couple of installments, they could be talking about the actual animations; if before installment 3 or 4, may just be their opinions about the renders, as they've always been top notch.