I have finished the Samurai Jack comic books. Before I begin, there are two different types of the comics: "Samurai Jack" and "Samurai Jack Classics", each with different quality.
The "Samurai Jack" comics was a fantastic read. Running for 20 issues, I liked every page of it. All I read felt like something Genndy would've made into actual episodes (like seasons 1-4). Each issue was either a standalone tale or a multi-parter (well written either way). Some parts felt like they predicted some events in Season 5 (the comics ran from 2013-2015, fyi) though I have very high doubts the way issue #20 went down will be similar to whatever we have in store for the Season 5 finale (comics are non-canon). Samurai Jack fans should totally give these comics a try.
"Samurai Jack Classics", on the other hand, I didn't like. In 2 volumes, this contained the "Special Director's Cut" comic book (which retold the the first 3 episodes of the show) and a huge bunch of short comics collected from the "Cartoon Network: Action Packs" comic books. The problem is that almost all of these comics feel like terrible fan-fictions who don't fully understand what made the show great. And it doesn't help most of the settings felt like it took place in the 21st Century rather than a unique/creative future and a number of the time Jack did feel out of character. I really don't recommend reading this.
Now to enjoy the rest of Season 5.