This will be brief.

Rating: 10/10 (4 August 2015)

One never tends to expect much from a movie staring Keanu Reeves. Why? I'm not sure, I think he does just fine and I'm usually entertained, but that's just me. This movie is, well, if you abhor violence, this movie is NOT for you. I don't like violence for no reason, but the violence in this movie IS the reason for the movie. It's fast, it's justified (bear with me) and it's amazing.
Others have given plot summaries but it seems almost required so; Former Hit man goes for revenge on the scumbag gangsters who wronged him and as it happens, he has a connection with them. OK. That's over with.
Not since "Shoot 'Em Up" has a movie been solely about the violence and not since "Shoot 'Em Up" has it been done so well. Even the faint of heart could enjoy this movie and trust me, I know people who cringe at violence in movies, my wife is THE prime example, and yet, you get lost in the action. It's non-stop. The few breaks between fights and shootings are seemingly filler, but necessary filler.
I had heard great things, but once I watched it today, I was VERY impressed. How do you root for a bad guy? Well, when he's killing WORSE guys, how can you not root for him? And yeah, he kills a LOT of them.
John Wick also displays a certain charm, not a 007 type of charm, but an all business charm. He will never mess with you if you're not a part of his business. Is that ETHICS? Sure, why not. He's not flamboyant, he's not over the top, he's all business, yet very civil, very refined and decent...unless you ARE his business.
I was far more impressed than I expected and I DID expect to be impressed. If you don't like violence, don't see this. If you don't mind violence so long as it has a purpose and moves the story, you'll LOVE this. If you LOVE violence, seek help and soon. You're potentially dangerous.