What have they done to you?
Besides the fact that this outfit is ridiculous just from the sake of physics. (I mean, we're talking about a character who does a lot of cartwheels as part of her schtick. Flipping upside-down + half a bustier held together with dental floss = well, you might as well just get it overwith and run around topless, why don't you?)
Skimpy outfit aside (I'm starting to get numb to them by now...or at least not so surprised anymore) this outfit throws away one major part of the character: her association with the Joker. Harley Quinn was a character who was indirectly created by the mind of the Joker. She dressed as, well, a harlequin to go along with the clown theme. Added to the mix was that she had a background in gymnastics, and basically her suit was a unitard. Makes sense, right? I've always been a stickler for a character's outfit being a representation of his or her motive or identity.
Now what does the above costume represent? I really have no idea. It just looks like a cosplay outfit to me, reminiscent of the Arkham Asylum video game. So what kind of statement does that make?
I got nothing. A lot of fans complained about the skimpy outfit, but no one has really said anything about her lack of association with the Joker. (I'm basing this on pure assumption, taking the next logical step from Gotham City Sirens.)
Somewhere along the line, it was decided that Harley Quinn should break free of the Joker, and I never quite understood why. Do fans want to see her on her own instead of playing second giant mallet to the Joker? (If that is the case, then Gotham City Sirens shouldn't be ending.) Do fans want to see her as an anti-hero? (Having Poison Ivy in the Birds of Prey aligns with this.)
Her relationship to the Joker was such a complex and deliciously twisted one that I was sad to see it go. The Joker was her main source of motivation: she did anything to please him, much to hilarious or tragic results. Cutting her off from the Joker completely leaves her drifting in thin air as a nothing but an motive-less psycho in a skimpy outfit. Though she had broken ties from the Joker in Gotham City Sirens, he was still a looming shadow of her past that still held some sway over her psychologically. She was still motivated in some way by him, however tenuous.
So what is it you're trying to say now, DC?