While Shepard's aim here is laudable, I think it's pretty clear he falls a bit short of the mark. The menacing Welch is one of his greatest creations, but the means by which he tortures and bedevils a rural couple and their "houseguest" are thoroughly unimaginative and under-cooked. Much like "States of Shock" (although this is FAR better than that misbegotten farce), there's also a fixation on male anatomy that's by turns obnoxious and dispiritingly obvious.
With that said, I'd probably lean towards 3.5 for this overall. It makes for a brisk read, and I think his emphasis on producing this before the 2004 election was wise. Nowadays, it's hard to imagine anyone getting the point or taking it seriously, media literacy having been under assault now for decades, but I find it heartening (as if there were ever any doubt) that Shepard was so staunchly opposed to the actions of the Bush administration at the time.
The Abu Ghraib imagery here in particular (hell, he even has the character who gets tortured call himself *Graig* throughout) feels clumsy, but what the hell else can you do with something like that? I think this works best when it functions as an expression of otherwise-ineffable rage and sorrow. The clumsiness is somewhat forgivable in that sense.