Barry Allen was introduced during "Arrow" season 2, which was the show in its prime. After setting him up in the universe, they went on to make a show based entirely around Barry Allen becoming The Flash. Since "Arrow" was getting darker and darker, "The Flash" went in the opposite direction. It's the tonal antithesis of "Arrow". 

Lighthearted, quirky, and silly, yet grounded enough to make us care, and the writing is just as sharp and witty as you'd hope.

Light and upbeat.

Like "Arrow", there are some soap opera-y moments, but they're placed sparingly enough in the series that they don't take you out of the show. The dialogue is silly sometimes but that's what gives it its charm. It's not supposed to be brooding and gloomy like "Arrow"; it's light and upbeat while still delivering truly awesome comic book moments. And the threatening villains remain threatening - the Reverse-Flash is legitimately menacing, and the tone shifts appropriately for the episodes that he's in. In short, the writing is consistently great while managing to throw a few surprises at you along the way.

Great, especially concerning The Flash himself.

I'm a big fan of DC comics and I was excited but cautious when they announced this show mainly for the fact that I wasn't sure they would pull off the effects required to make a convincing Flash with a TV budget but my worries were quelled from the first episode. Other than a few of the villains abilities, the special effects in this show are great, especially concerning The Flash himself.

The acting itself is surprisingly great.

When the characters were first introduced in the "Arrow" episode, I thought I would hate them in "The Flash". But after a few episodes, each character is developed with a certain role in the show, and it works wonders. Harrison Wells as the enigmatic mastermind behind STAR Labs, Caitlin as the straitlaced neurotic scientist, Cisco as the sarcastic pop-culture referencing comic relief who comes up with each villain's "super" name, and Barry Allen as the relatable everyman who was struck by lightning and became the fastest man alive. Then there's Barry's family - journalist Iris West, his foster sister and secret love of his life, and the detective with a heart of gold Joe West, his foster father. The best part is the chemistry between them all. There are clashes between the strict Wells and the snarky Cisco, Barry and Iris' boyfriend Eddie who you're not too sure about at first, and Eddie and Joe West with the usual "you're dating my daughter" dynamic. But none of it comes across as artificial. 

You believe all of the character interactions because they're developed well enough so that you're fully aware of how each person would react to each situation, and the writers are spot on when it comes to their motivations and actions.

The acting itself is surprisingly great. It's refreshing in a CW show to have a likable good actor as the lead, and Grant Gustin knocks it out of the park. He's usually upbeat and quirky but when he's given the important emotional beats, he pulls them off well enough to tug at your heartstrings. Everyone else is great too, even the "freak-of-the-weeks" like Captain Cold played with appropriate coldness by Wentworth Miller. The writing is also excellent for the most part. It takes a few episodes to get going but once it starts up it does not slow down. As the story starts to unravel and the plot slowly reveals itself, it's hard to take your eyes off the screen. There are more than a few jaw-dropping episodes such as the season 1 finale, and superb looking special effects and CGI monsters, namely Gorilla Grodd and King Shark.

Must-watch for DC fans.

The story and various plot devices are fun and the characters are mainly likable. 

"The Flash" is a must-watch for "Arrow" fans, comic book fans, or action sci-fi fans in general. It's a fun take on the superhero genre and once it hits its stride, it delivers some of the coolest superhero ideas ever explored on TV. Sure, there's some filler, there's corniness. But when it's supposed to be emotional, it is. When it's supposed to be badass, it is. It's not a perfect show by any means, but it delivers on exactly what it sets out to. "The Flash" is a blast.