This really is excellent stuff, and it's a bit of a shame (as with many of these older programmes) to watch it one episode a night for a couple of weeks, rather than one episode a week for three months as the makers intended. It means you pick up a bit more than necessary on the differential rates of aging among the main characters - Tiberius, for instance, shifts well from aspiring princeling to debauched old emperor, but Augustus as an old man just looks like a young man with make-up. And Caligula and Messalina are not quite young enough for the parts (John Hurt was 36 when it was filmed, Caligula 29 when he died; Messalina is clearly intended to be a teenager though Sheila White was 28); while Antonia starts off too old.
But it is easy to suspend your disbelief. In particular, it's impossible to take your eyes off the two leads (who both won BAFTA awards) - Siân Philips as Augustus' wife Livia, who poisons her way anguishedly through the first few episodes, and then Derek Jacobi as her grandson Claudius, watching in horror as the reigns of Tiberius and Caligula degenerate, and even more horror-struck when he ends up as Emperor himself. It's all really good, even some of the minor characters - particular kudos to Ashley Knight who plays Claudius as a young boy, complete with twitch and stammer.
It's startling to realise how close it is to the source material in places. Suetonius actually records the correspondence between Augustus and Livia about what the heck they were going to do with Claudius - as the imperial archivist a century later, he presumably had access to the original documents and didn't just make it up. There's a really good internet resource comparing the TV series with the actual historical facts (as far as they are known) here. My one regret is that I bought the Dutch-language version of the DVDs rather than the English version, which apparently has lots of brilliant extras.