I just listened to this the first time recently, and it might be my favourite out of the initial main range's first 25 audios or so. What particularly works for me about it is that not only is it just a solid Silurian story, it has a lot of fun ideas marrying these lizardmen to Charles Darwin’s work as a scientist. It is really, really cool and in my opinion well done how the Silurians cause a crisis of faith within Darwin and that becomes the emotional centre of the whole audio.

The stuff with the Silurians creating humans was a little wonky and underdeveloped as an idea that feels like it should be a bigger deal.  It didn't feel like the best decision for continuity, but not so much it ruined the experience for me.  It's a strange choice, but not a prohibitive one.