"Is it addictive?"
Yes!
But I thought series 8 was weaker in many episodes then 1-7. Fingers crossed that the current one (9) is stronger.
(Warning: if deciding whether DC should watch: the DVD box sets are a 15. When episodes go out on the various Ch4 channels which show them daytime and early evening, there are cuts removing the most explicit language. So broadcast can be more suitable than DVD. Some episodes have a lot of sexual themes and references, others are harmless).