Claudius is a difficult emperor to understand. This is not because the tradition is ambiguous: Claudius is presented universally as a bad emperor. But there always appears to be that but more going on than is at the forefront of the analysis of the sources.
Ancient criticism focuses on personal relations and family issues. We are used to evaluating political leaders by other criteria. There is a danger of carrying over the prejudices of our ancient sources into our understanding of Claudius. Undoubtedly, the death of Claudius let loose a torrent of abuse. The Neronian regime praised and mocked him, proclaimed their difference from him while drawing power from his legacy.
It is easy to to write revisionist histories of Claudius, dismissing the criticisms as gossip and finding reasons to praise his political and administrative management. Some of his activities seem more modern, especially in administrative and infrastructural issues. What should serious people do with the stories around Messalina and Agrippina? In relative terms, his reign was massively successful if we compare him with Gaius and Nero.
But is it right to ignore the ancient view?
He was undoubtedly an authoritarian emperor. The tradition consistently represents him as paranoid in his politics. He lacked mercy in his dealings with his opponents (it is surely not coincidental that Seneca chose to advise Nero through a treatise De Clementia [On Mercy]). Suetonius (Claudius 29) tells us that Claudius had executed 35 senators and 300 equestrians. We cannot be confident about the figures, especially the equestrians, which is a suspiciously rounded number), but these figures are high. If we assume that there were 600 or so senators, we are looking at the execution of about 5% of the senatorial group. That should give us some pause for thought.