Devolution or Devolution?

Boris Johnson is facing the heat after reportedly calling Scottish devolution a disaster, causing anger from Labour and the SNP, as well as creating a potential headache for the Scottish Conservatives ahead of the 2021 Holyrood elections. But just how successful has devolution been? As political parties become more polarised, and even the pronunciation of the word itself called into question by the team, can there be a grown-up discussion on devolution in the UK?