First things first.... The movie is not suitable for 13+. It should be rated 16+.
Now to the review.
It's a long movie and it tends to get stretchy and story gets you nowhere. So many characters without any defined purpose.
Writer has tried to mish-mash marvel characters and actual human history and attributed lot of our history to eternals. I find it kind of childish.
Characters don't have any purpose and there are too many of them. It seems like marvel wants to make few more of these. May be then the story will become clearer. But for now, it's an incomplete story. That's not how a movie ought to be, especially when it's so long.
And Arishem... The all powerful god of the movie - I just wondered, why, Arishem, creater of our beautiful Earth, looks so LEGO like. Apart from that the visual effects are superb. So one star for that. But you need some story as well.