You got a source for that $6 billion? I've tried searching around and can't find that anywhere.
Every study I've ever seen has shown that funding the IRS is a net benefit to tax revenue. So my instinct is that the $6 billion you saw included more than just this particular campaign.
I played this during last Halloween. It's great for having really cool Halloween-themed art and sound.
Everything else- the level design, story, physics, abilities, combat, bosses... They're all perfectly acceptable for a 3D platformer. Nothing particularly bad, but nothing particularly great or noteworthy. Still I'd say it was worth at least $10, maybe $15.