Could someone help me understand Dencun better?

Hi, I've been looking at ETH's next 'upgrade'. It's almost Q1 of 2024, and still all I see are generic statements like "It will improve tx fees, simplify rollups, and have generic housekeeping updates".

As someone who's genuinely interested but likely unable to follow the dev livestreams, could someone help me understand the deets?

How would the upgrade improve fees? Are there any interesting mechanistic changes? If gas comes down, by how much? What is going to change that makes rollups easier?

To be clear, I'm not expecting an eli5..... You can assume I am familiar with most crypto-related terminology and concepts. It's just that I am stuck at a limbo level between the highly technical dev discussions and the low effort vagaries of news articles. I wonder if there are others in the same boat.

Thanks in advance to any kind folk who take the time to help me.