Definitely worth watching. If you enjoy Tarantino or Frank Miller's work, this should be a solid entry for your entertainment.
Mads Mikkelsen was excellent and carries the film very well. There are moments of subtle, dark humor and the majority of the action was well executed. While this film carries with it the tropes of gratuitous sex and gore, I still felt invested in the protagonist's purpose.
I've read multiple reviews for this film and I was surprised that so many were quick to cast it aside, most notably the reviewers contributing to Rotten Tomatoes. When reading many of the critiques, I sensed a genuine lack of appreciation for the genre. Among the most egregious of complaints is that it was "overly stylized", which plainly ignores the fact that graphic novels and their film adaptations are such by design.
One head-scratching moment I experienced is when the lead character, a very well-traveled assassin, needs to be reminded where a certain eastern European country is on the globe. I understand at times the need to give the viewer a geography lesson, but this would have been better delivered as an on-screen title rather insulting the intelligence of the lead character. In addition, I never felt truly threatened by the chief villain. The attempt to portray a deranged leader of a company of assassins ultimately made him seem silly and only in control for a couple brief moments.
To my fellow audience members and critics, don't overthink this one. While it may only be worth a single time through, sometimes that's enough.
But don't take my word for it. Watch it.