"Putin said the plane would cost up to three times less than similar aircraft in the West and could remain in service for 30 to 35 years with upgrades, according to the report."
Analysis: We cut corners on safety, quality, and reliability in order to build more of them than the West, in a shorter period of time. "Upgrades" will be released as soon as the design specs of Western upgrades can be obtained, reverse engineered and retro-fitted into the airframe.
I guess there is only one way to find out... Probably never know for sure.
That all depends on who they sell / lend them to.