The kit is good and , in Russian hands, worth thinking about. But most of their sales are in small numbers to people like Algeria, Egypt, Iran, Indonesia. History shows that these countries have serious problems in keeping any advanced aircraft in service in meaningful numbers (even the USAF has problems with the F-35) so realistically they're not much of a threat.
The Panda in the room is of course licence -built Russian aircraft in China. Since the Chinese haven't fought an air war in decades we have no idea what their performance might be with modern kit.