It was still a monumental achievement considering the *ENORMOUS* difficulties Hawker and Rolls-Royce experienced developing the Pegasus engine and the P.1127 Kestrel airframe around the engine. Even more so considering the technology of the Tumanski engine was less advanced than the Rolls-Royce engine.
It was more a technology demonstrator than anything else. The fact it actually worked had to surprise a lot of Western observers considering the many issues Rolls-Royce had to overcome to get the Pegasus engine to work with the P.1127 Kestrel prototype.