"One Nation... Under Dog." YES! Perfect, perfect, perfect. Everything you want in a tagline: It's cute, it's clever, it's just dopey and eyeroll-inducing enough to permanently brand it into the brain of anyone who reads it. I'm literally smiling or outright laughing every damn time I read it. And it's the perfect compliment to the poster itself, both of them deftly capturing the promise of canine-themed ribbing of Superhero Movie bombast. As poster art goes, this thing is gorgeous, so perfectly evocative of the "Spider-Man"/"Superman Returns" key art design schematics that it actually takes the eye a crucial extra moment to realize that it's an adorable puppy-dog in a cape perched on that familiar-looking gargoyle instead of an angst-ridden costumed-vigilante.
I'll confess to having been extremely fond of re-runs of the cartoon, one of those gloriously bizzare dialogue-heavy mid-1960s network cartoon quickies, as a young'in, so it's a little "odd" at first that they're going the route of a "real" dog turned "super," though it does seem the only way to capture in live-action the odd concept of the show where Underdog is an anthropomorphic dog in a world of "normal" humans. And it's undeniable that the little fella IS too cute for words, overall a fitting remedy for the fact that Superman's dog Krypto will likely never see screentime in a live-action feature. I know it's unwise to trust that Disney will make something good out of this, but they did just produce one of the best superhero spoofs EVER in "Sky High," so you never know. Bottom line: A movie that actually delivered on what this poster promises would be friggin' awesome.
BTW, I agree with AICN's Merrick: Almost as awesome as that tagline is the prospect that, if this really is the final "hook" line for the movie, the "religious right" will pitch a fit over "mocking a reference to the Almighty." That's my kinda icing.