Why is Iron Gold not liked?

Listend to graphic audio part 1 till now (so around half the book i think). And i love the setup, also having more characters is amazing. As much as i love Darrow its fun getting more perspectives, with Lysander, grey heist dude and red girl (sry not good with names...)

But most book rankings i see puts Iron Gold as the lowest. Do people find the book bad or boring? Or just worse then all others? + Seeing i like the pt. 1 will the book grow worse or stronger with the rest of the book?

P.S.: Pls dont spoil Iron gold =)