Oldman (naturally) carries every scene he's in but the rest of the cast are a mixed bunch - some solid character actors and good for a bit of comedy but others hopelessly hammy or else wooden. The villains are generally stuffy, upper-class creeps or, their dreaded ally, the Working-class White Male. However, the main problem with each season in the plot - it often starts off promising enough, but, by the final episode, has descended into extreme silliness, by which time it is hard to maintain interest. Apart from the all this, the whole premise of the series is a fairly scurrilous attack on the UK security services and the UK more generally. I've no doubt this series has been dubbed into Russian and Persian and gleefully shown on TV in all anti-Western regimes. It's a massive propaganda own-goal for the UK - your enemies must be delighted!