Turning the predators into ancient astronauts was the worst bit imo.
I always had a soft spot for that von Daniken thing - I blame Stargate - so that never really bothered me. That said, there's no denying how cool those sets looked. I'm sure they could have made an awesome spaceship or colony set for that film. They did such a great job with the cash they had
I dont mind the idea of ancient astronauts in fiction, like with prometheus. I just didnt like the idea of it being the predators. Having them guide our early civilizations wasnt something i liked or wanted regarding their lore. Otherwise i really enjoyed the armor and weapon designs even if the effects looked a little fake.
The sets were also great. I do think the film could have been amazing with some slight changes in, setting, tone, and execution.