So! There are like three threads (Including the news room one) about whether or not Skull Girls is sexist, but not about the game itself. I did some digging and...I really like what I found about the game. It seems really cool, AND it finally did something that I've been waiting for a fighting game to do since forever. More on that later.
The world in Skull Girls isn't especially serious, although there are some dark tones going about in the background. Backstory time!
So! Game mechanics. There are over 250 different combo lines ("Lucky" for 7, "Barely Legal" for 18, "Devilish" for 66, etc; the game can somehow detect when an infinite combo is getting started (The color of the 'hits' change) and allows you to break them by 'Bursting'.
But! The one I like the most is...you can choose either one character, or a team of three. If you pick only one character and the opponent picks three, then your one character will be powered up to the point where they can actually take on three opponents at once. Wanted a fighting game to do that for so long...
Anyway! That's all I know. Share away.
Edit: I was wrong! You can have a one man, two man, or three man team. Not just one or three.
Edit 2:
The developers consider Skull Girls' setting to be 'Dark Deco'. Which...is a subgenre they've made of Art Deco. Since I suck at explaining things...! http://en.wikipedia.org/wiki/Art_Deco
That goes into music, as well.
The composer is Michiru Yamane. She did the soundtrack for Castlevania: Symphony of the Night.
'Eeeeeey. Gameplay mechanics video.
The world in Skull Girls isn't especially serious, although there are some dark tones going about in the background. Backstory time!
Overall story: There is a mystical artifact called the Skull Heart that will grant it's user any wish. However, if the user's heart is even the slightest bit impure, then the Skull Heart will corrupt the user and their wish. An impure user turns into a Skull Girl, a monster with the power to end the world. In this world, there was a war between three nations (There are only three in the world) called the Great War. However, the Queen of Canopy Kingdom wanted the war to end, so she obtained the Skull Heart and wished for the end of the Great War. However, the Skull Heart turned her into a Skull Girl and granted her wish...by driving her to destroy most of the world, forcing the three nations to join together to oppose her. A few years after that, there are rumors of a new Skull Girl, which is what kicks the game into motion.
Character Bios:
Princess of Canopy Kingdom and daughter of the previous Skull Girl, it's Parasoul! She's armed with a living umbrella named Krieg who can cry napalm, and also commands a battalion of elite Canopy soliders. She's also a closet geek who watches a lot of cartoons. Such is life.
Filia is a random schoolgirl with amnesia. SO ORIGINAL. Anyway, the reason she has amnesia is because of a demonic parasite named Samson that attached himself to the back of her head. Whatever Samson eats or drinks affects Filia, so that's why she's pudgy and gets drunk rather often. SAMSON LOVES HIS BOOZE.
Surrogate daughter of a mafia boss who wants to be romantically involved with her dad. Squicky. She was an orphan raised on the streets, but is now famous. If you're wondering how her clothes are being held up, it isn't by that strap on top of her shirt thing. That actually comes off...
Valentine is the last surviving member of Last Hope, an elite anti-Skull Girl task force. After watching the rest of Last Hope get slaughtered, she went rogue and joined the current Skull Girl. Or maybe she was a traitor all along...
Once a normal schoolgirl named Carol, she was kidnapped by Valentine when she was still working for Last Hope and turned into the biological monster known as Painwheel. She was meant to be an anti-Skull Girl weapon, but she's...a bit too insane for that.
Peacock was a war orphan named Patrica until she was kidnapped by slave traders who picked her up off the streets and mutilated her beyond recognition. She was found and saved from death by Last Hope, but had to be turned into the cybernetic monstrosity known as Peacock in order to survive. The only parts of her body that remained intact were her brain and part of her face. She was meant to be an anti-Skull Girl weapon, but, like Painwheel, is insane. She also really likes killing people. A lot.
Sidenote: For those who are curious, yes, she does have a bear trap for teeth.
A former member of the Fishbone thieves, their last job was to steal something called the 'Life Gem'. After obtaining it however, the mafia murdered them all to get it back. Fortunately, Ms. Fortune swallowed the gem, granting her superhuman regenerative abilities. The mafia tore her to pieces, but she managed to survive thanks to her new power. Yes, that mafia that killed her friends is the same one that Celebella is a member of.
The current Skull Girl, Bloody Marie. Don't know much about her besides the fact that her main weapon is a vacuum cleaner.
Character Bios:

Princess of Canopy Kingdom and daughter of the previous Skull Girl, it's Parasoul! She's armed with a living umbrella named Krieg who can cry napalm, and also commands a battalion of elite Canopy soliders. She's also a closet geek who watches a lot of cartoons. Such is life.

Filia is a random schoolgirl with amnesia. SO ORIGINAL. Anyway, the reason she has amnesia is because of a demonic parasite named Samson that attached himself to the back of her head. Whatever Samson eats or drinks affects Filia, so that's why she's pudgy and gets drunk rather often. SAMSON LOVES HIS BOOZE.

Surrogate daughter of a mafia boss who wants to be romantically involved with her dad. Squicky. She was an orphan raised on the streets, but is now famous. If you're wondering how her clothes are being held up, it isn't by that strap on top of her shirt thing. That actually comes off...

Valentine is the last surviving member of Last Hope, an elite anti-Skull Girl task force. After watching the rest of Last Hope get slaughtered, she went rogue and joined the current Skull Girl. Or maybe she was a traitor all along...

Once a normal schoolgirl named Carol, she was kidnapped by Valentine when she was still working for Last Hope and turned into the biological monster known as Painwheel. She was meant to be an anti-Skull Girl weapon, but she's...a bit too insane for that.

Peacock was a war orphan named Patrica until she was kidnapped by slave traders who picked her up off the streets and mutilated her beyond recognition. She was found and saved from death by Last Hope, but had to be turned into the cybernetic monstrosity known as Peacock in order to survive. The only parts of her body that remained intact were her brain and part of her face. She was meant to be an anti-Skull Girl weapon, but, like Painwheel, is insane. She also really likes killing people. A lot.
Sidenote: For those who are curious, yes, she does have a bear trap for teeth.
A former member of the Fishbone thieves, their last job was to steal something called the 'Life Gem'. After obtaining it however, the mafia murdered them all to get it back. Fortunately, Ms. Fortune swallowed the gem, granting her superhuman regenerative abilities. The mafia tore her to pieces, but she managed to survive thanks to her new power. Yes, that mafia that killed her friends is the same one that Celebella is a member of.

The current Skull Girl, Bloody Marie. Don't know much about her besides the fact that her main weapon is a vacuum cleaner.
So! Game mechanics. There are over 250 different combo lines ("Lucky" for 7, "Barely Legal" for 18, "Devilish" for 66, etc; the game can somehow detect when an infinite combo is getting started (The color of the 'hits' change) and allows you to break them by 'Bursting'.
But! The one I like the most is...you can choose either one character, or a team of three. If you pick only one character and the opponent picks three, then your one character will be powered up to the point where they can actually take on three opponents at once. Wanted a fighting game to do that for so long...
Anyway! That's all I know. Share away.
Edit: I was wrong! You can have a one man, two man, or three man team. Not just one or three.
Edit 2:
The developers consider Skull Girls' setting to be 'Dark Deco'. Which...is a subgenre they've made of Art Deco. Since I suck at explaining things...! http://en.wikipedia.org/wiki/Art_Deco
That goes into music, as well.
The composer is Michiru Yamane. She did the soundtrack for Castlevania: Symphony of the Night.
'Eeeeeey. Gameplay mechanics video.