What a mess. A cute and enjoyable mess, but a mess nevertheless. Terius behind me is clearly a comedy, through and through, to the point that there's a chance to laugh even to the more serious aspects of the drama. If you're expecting a spy drama of sorts, I highly suggest you find yourself a safehouse somewhere and hide from this drama alltogether : the focus is elsewhere. As it happens, that's also the enjoyable bit : a sweet comedy, relying on a spy background to provide quirky scenes and situations (still with some action, bland as it was), and misbehaved cute children for some endearing moments.
So here's a spy trade secret to enjoy this drama : don't expect anything from the scenario, overly simplistic. It's merely a pretext to the scenes and situations mentioned previously. It's still enjoyable, but way too weak to entertain even the less experimented detective tv-show fans.
Along with the bland and predictable twists of this script comes the sentiment of unrealistic behaviors the show gives off, quite often. It may not exactly be a serious issue - don't forget, it's almost a comedy - but that still could affect your "immersion" into the show. At times, the unprofessional and idiotic behaviours from the members of an intelligence agency (emphasis on intelligence) could most likely ruined the entire emotion that the scene was supposed to provide.
Eventually, what remains enjoyable in this show is, in a single word, relationships. The interaction between the main leads and their support. From the extravagant but honest housewives information network, a mother and her children, a spy and these children, and eventually everyone that cross their path. The relations between a single man with an extraordinary but lonely life into the ordinary life of a friendly widow.
To that aspect, the performance from both the main actors (equally, despite what others may say) and support was quite good, and maybe even slightly better from the support characters, since an important part of what makes this drama enjoyable, clearly comes from the tenderness, the cuteness of their respective roles.
Since these relationships and the feelings that followed were to me a better and more enjoyable surprise than the investigation scenario itself, I can't exactly spoil the only bits of enjoyment this drama could provide to you, so ...
it's up to you if you care enough to follow Terius, moving behind him and past this review autodestruction in 1 sec.