IndieWire by Liz Shannon Miller

That quest for the extreme can sometimes feel like a distraction from the attempts at real emotional storytelling, but when it all comes together, it’s a whole lot of fun.

Entertainment Weekly by Darren Franich

The bad behavior is fun, but the plot construction can feel thin. ... But, um, there's a unicorn! Oswalt give Happy a sweetness edging into lunacy. ... To quote Home Alone 2, another yuletide tale about a heroic psychopath torturing bad guys in New York City. [8 Dec 2017, p.46]

Yahoo TV by Ken Tucker

This first episode is such accomplished, vigorous fun, I highly recommend that you give it a look. I also guarantee you’ll wince a few times at what Nick goes through, and you’ll be glad he’s now got a chipper Happy in his life.

The A.V. Club by Andrea Reiher

Three episodes in, the jury is still out as to whether the second season will find the urgency and emotional stakes that the first season had but things are looking up. At the very least, the new Smoothie-Hailey story arc is quite intriguing and has the potential to go to some interesting, entertaining and even dark places.

IndieWire by Ben Travers

At best, Happy! is flying toward something bigger than what it finds in these first two episodes; a point or a connection or an original conceit beyond the entertainingly over-the-top nature of its core story. At worst, it’s just throwing a bunch of blood at the wall and hoping the shock is what sticks. Either way, it will be fun to see how crazy the Syfy series can get before it blows its top.

TVLine by Dave Nemetz

The action in the pilot is so breathlessly high-octane, it’s borderline exhausting. The pitch-black humor and dystopian funk veer dangerously close to ugliness at times. And outside of Smoothie, Nick’s antagonists are too thinly drawn to make an impression. ... But if you like your TV dramas gory, action-packed and ruthlessly funny? Meet your new favorite show.

Boston Herald by Mark A. Perigard

Happy! captures the tone “Marvel’s the Punisher” should have aspired to: grisly, gross and nutty without abandon.

The A.V. Club by Danette Chavez

When all of its parts are working in unison, Happy! is a stylish mix of violence and unhinged humor, which, while not exactly a fresh concept, still manages to be engrossing.

San Francisco Chronicle by David Wiegand

SyFy made two episodes available for review, and they were both over-the-top and funny. The only question is whether the show is too high-concept for the long haul. That’s always the potential danger of high-concept shows, but if the writers can keep coming up with workable story lines, viewers will have reason enough to stay happy.

The Hollywood Reporter by Daniel Fienberg

The level of crazy in Happy! isn't inspired enough, nor is its story interesting enough to measure up to the genre's best, but in Meloni, it has a star capable of measuring up to any outlandish competition.