It's not that they don't "like" the PAK-FA, the "Russian Specialists Familiar with PAK-FA" are noting to the Janes reporter that the PAK-FA lacks systems critical to a fifth gen standard, and that the IRBIS radar and F-117S are already flying aboard the SU-35.
to summarize what I've been stating for years, they "the Russian Specialists" are venting their frustration to Janes.
The F-22ski, looks like a duck, and quacks like a duck, but in reality? "it ain't a duck?"
It is a very beautiful, agile, fast Flanker, nicely done, but its L/O and electronics are just not up to standard.
In contrast the J-20 is a very serious effort to get into the fifth gen ball-game?? but it is a first gen L/O aircraft, China has "clamped down" on data breaches via the "wall climbers", so we are left to speculate on whether or not they have been successful, or how successful they have been. The Russian specialists have been very frank on the other hand.