Disclaimer: I love this show. I love the characters and the universe and children's cartoons so you won't have me raving on how bad this show is... because it's not.
1. It's extremely funny in a decent way (unlike some other shows on cartoon network COUGHteentiansgoCOUGH). It has just the right amount of hilarity to action, and don't even get me started on Firestorm.
2. The characters are really great, but you probably should have some understanding of the DC universe. Batman is pretty much Batman the Animated Series Batman (Episodes: Time Share and Rage of the Red Lanterns) and Superman is really the boy scout that I personally love. He's not just powerful and he doesn't have a god-like detachment and seriousness. He's funny, light-hearted, and ready for action. Wonder Woman is great. She's pretty much a mix between Batman and Superman but is an incredible character all her own. (Episode: The Trouble With Truth) I love love love the junior justice leaguers Stargirl, Firestorm, and Blue Beetle. (Episode: Field Trip (Firestorm: Freezer Burn & Nuclear Family Values, Stargirl: Supernatural adventures in babysitting, Blue Beetle: Time Share)) They're inexperienced but ready to learn and make jokes along the way! In the show, many characters that you wouldn't know about as a casual fan pop up. Plastic Man, Booster Gold, Constantine, and Space Cabbie are just a few of many excellent characters in both comedy and contribution to a larger universe. This show made me appreciate Green Arrow (Episode: Booster's Gold) and has many tie-ins to classic Silver Age justice league comics (Episode: Abate and Switch (They swap costumes))
3.THE ANIMATION. The style and smoothness of the animation is the retro-classic-adventure that I personally love soooooooo much. When characters move swiftly, they are portrayed as a blur (a lot cooler than it sounds) so it looks fast and fluid. It's colorful in a good way and the backgrounds are really nice. I like the "poses" they sometimes do and it shows some character's powers in a really neat way. (Vixen especially, Episode: Garden of Evil)
4. Voice acting. I've heard bad voice acting. This is AMAZING voice acting. Also, Kevin Conroy and Mark Hamill. Need I say more?
I could probably go on for ages about Shazam, Flash, Plastic Man, Green Arrow, Zatanna, Swamp Thing, Green Lantern, Supergirl, Streaky and Krypto, Mr. Mxyzptlk, Riddler, Jonah Hex, Harley Quinn, and I'm ranting again. I really hope that if you're into comics, you'll at least try this excellent show.
I could probably go on for ages about Shazam, Flash, Plastic Man, Green Arrow, Zatanna, Swamp Thing, Green Lantern, Supergirl, Streaky and Krypto, Mr. Mxyzptlk, Riddler, Jonah Hex, Harley Quinn, and I'm ranting again. I really hope that if you're into comics, you'll at least try this excellent show.