"Never before has a man been able to walk with dinosaurs" sort of thing.
"Look how realistic it looks".
The audience in cinemas walk out (not before the end) going "Wow".
Then 5, 10, or 20 years later you watch it and laugh at the appalling special effects.
Back in the early 1980s my brother and me were watching Flash Gordon and the Claymen. Here's a description
The serial was Flash Gordon and the Claymen, which was quite scary as the Claymen materialised from the walls of caves. Flash's spaceship had been shot down by rocket ships of his enemy, the merciless Emperor Ming and Flash had taken refuge in a cave with the Professor and Dale Arden, his female assistant. Just when he thought they were safe, the Claymen appeared from the walls and surrounded them. The episode ended.We had been warned of this scary film by our dad who had seen it in the Penn cinema in the early 1940s.
All I can say is the special effects on Dr Who in the 1960s looked like no-expense-has been-spared-state-of-the-art in comparison.