They're both k-drama action. If you liked this then you'll certainly like IRIS but I can't say it'll be the same vice-versa. They are both big budget productions but IRIS is certainly way better in its execution.
they are kind the same:)
1. both main role want to revenge their too family
2. the bad guy and the good one are in love with the same girl and are x best friends
3.the same actio-romans kind
and much more
Both are action packed dramas with large scale conspiracy behind the scenes. The main protagonists of both dramas are victims of this conspiracy and are out for revenge. Romance is also an important part of both dramas, although maybe a bit more in Iris than in The K2.
Fabulous Acting.
Great Storyline.
Spy Thriller.
Though Rookie Agent Rouge is set in the 1930s. Rookie Agent Rouge is AMAZING though and you won't be disappointed if you give it a try.
Both have big budgets and good action. They both drag out a bit longer than necessary in my opinion but I'd still rate them both somewhere between 8-9/10. They also both have good directing.
Both dramas have leads who seek revenge for being framed. There's also romance thrown in. Also, lots of people die. The endings of both are sweet but tragic.
Both are crime related dramas where the protagonists are up against an extremely powerful and influential organization that's behind some huge conspiricy. Also, both will keep you guessing.
Both have lots of action. All In is a Korean mafia Godfather drama starring Lee Byung Hun and Song Hye Kyo. It's excellent but most people don't know about it since it was produced in 2003.