China are certainly a long way off from innovating something better than the United States - its alot easier to play catch up - they maybe good at
contructing tried and tested airframe designs but are 10's of years off the level of creativity, innovation and expertise that the americans have.
The J-10 looks a very basic air craft by modern standards - more worrying would be the capabilities of the internal avionics that are probably
surpassed by F-15's. Its more about the internal package of aircraft these days and BVR capabilities.

