Well, it seems to be a great aircraft accept they can't hardly get it off the ground. Severe problems with the engines. Major problems with the Radar/air to air missiles etc. etc.. Same as with the F35. Trying to go so hi-tech that it is beyond our current technologies. Remember that Russia/Soviets have always been an overwhelm by numbers philosophy (same as the US in WWII).
If you get into the history of Russian/Soviet technology they and the Chinese have been on a reverse engineering program since WWII. Hell they reproduced the B-29 (search Soviet B-29) and could never make it work. They (Chinese/Russians) have the same problem today. Material engineering is beyond their technology. Engine fan and turbine blade technology is far beyond their engineers at this time. The only way they are certifying aircraft for Western use is with Rolls Royce or Pratt and Whitney engines. The Russians and Chinese can copy but they can't figure out the metallurgy required for the high temps. of modern Hi-bypass turbo fans.
The Mig 25 was an awesome interceptor but it required new engines after just a few flights, compare that to the F-15 that could fly thousands of hours with the same engines. There is no comparison to US V Russia V China except one terrible scenario. The Chinese could build so many aircraft that the US or Japan or Korea would run out of missiles. This is a big problem. Throw up crap for the adversary to shoot down and then, when the adversary is out of high dollar missiles you can then own the sky.
Sorry for the rant, I have just read a bunch about this subject.
Karl
