I think the idea for this show is great. It's a mix of scripted and improv with the guest playing the role of the PC assisting the DI investigating a murder. The guest is on their own and tries to play the part without laughing at the numerous funny situations and dialogue, at the end they have to choose who they think the killer is. It's often funny but varies by episode, some barely are, others I laughed quite a bit. It's also fun seeing the same few character actors try to play a lot of different celebrities, often ones from the US. Overall, I enjoyed it and wish they made more episodes.
That said, a consistent flaw in the show is the murder mystery aspect. If you're hoping to be able follow along and try to figure out who it was, the guests often do not gather enough clues, getting distracted by the humorous parts and the DI, and little details in a scene are hard to notice due to the darkness (going for a classic crime noir look but went too heavy on it) and camera angles. The characters being investigated also tend to be overly eccentric and uncooperative though at least 1 thing will make it seem like it could be them. This results in the guests being wrong most of the time at the end when they have to choose the killer.