Why would Batman not make a good member of the Sinestro Corps? Because there's no way he'd belong to a group that's named after someone else.
As a young boy, Bruce Wayne saw his parents fall victim to a senseless crime, his focused purpose became to avenge their deaths
by fighting Gotham's criminal elements as Batman. The people of Gotham City see Batman as an almost mythical figure, able to tame any adversary, no matter how powerful. To thwart crime, he relies of his awesome deductive powers, sheer physical speed and an assortment of high-tech weaponry and unique crime-fighting aids.
That bio's not actually from the back of the packaging, per se: while it is what's printed there, it's inexplicably covered by a big Sinestro Corps logo. When the oddity was first revealed, some people thought that this costume was from an upcoming story arc and Mattel was keeping the details secret by hiding them behind the logo. Of course, those people are stupid. It's a made-up costume that has no specific bio text, so Mattel was just hiding the fact that they were reusing existing copy. This is the world's greatest detective, guys - if you fall for idiotic conspiracy theories, you dishonor his memory.
Sinestro Corps Batman uses the same body as the other DCUC Batmen, with the only new sculpt being his forearms: the gauntlets are a merging of the Sinestro Corps' banded style with Batman's arm-points. He uses the Sinestro Corps belt instead of one of his many utility belts, but that's a piece that's just glued in place.
Something that will draw a lot of customizers to this figure, though, is the new head. Sure, the Batmen we've had before from Mattel's various lines have been grumpy or unhappy, but this one is furious! He's got his teeth bared and his brow is furrowed. This is Bruce in full-on "I'm going to make you fill your pants" mode, and that's never been done before.
Like we said, this is Batman in a made-up costume.
He's dressed like every other member of the Sinestro Corps, which makes him great for stashing in the middle of your Sinestro Corps display, but is otherwise a bit dull. See, in Green Lantern #17, a Yellow Lantern ring came to Earth in search of a host - naturally it picked Batman, and he briefly (as in, the span of a few seconds) wore a Sinestro Corps uniform. But that was back when the uniform was blue, not yellow, like Sinestro's old gear. So yeah, he has worn a Corps uniform in the comics, but it wasn't this Corps uniform - this is just somthing made up by Mattel. Consider it DCUC's first Elseworlds toy.
Sinestro Corps Batman gets one accessory: a ring construct batarang. Well, maybe a batarang. It's some big, bladed, bat-shaped thing, so "batarang" seems like the most appropriate descriptor. It fits over his right hand (yes, Sinestro Corps rings are always worn on the left, but Bruce has never been a joiner), and has the usual "energy flare" spikes all over. The plastic isn't as translucent as it should be, though: compared to Karu-Sil's companion, the yellow plastic is cloudy, and that's disappointing.
Because this Batman design is 100% fabricated, his DC 75th Anniversary collector button is fabricated, as well. There isn't a single panel of comic art that they could have pulled an appropriate image from, so we get just a plain image of Bruce standing around with a gleaming Parallax logo behind him.
Interestingly, though the Series 15 BAF, Validus, uses a mold seen several times before, the chest isn't reused. How's that possible? Well, Brimstone's head was molded as part of the torso, Kilowog had wrinkly neck-skin and Arkillo had a collar and zipper, so this is the first time there's been a totally unembellished release. How about that! The abs are black, the chest is gray and purple.
At one point during the planning for Green Lantern: Rebirth, the plot would have seen Batman possessed by Parallax, giving him firsthand experience with what Hal Jordan had gone through. That never happened, but then, nothing about this figure ever happened, either. Imagine this toy is a release from an alternate universe Mattel, based on a story where Bruce was possessed and remained a member of the Yellow Lanterns. Maybe even the founder.