I loved this for its levels of general stupidity and tongue in cheek attitude. Its a movie that doesnt take itself too seriously, isnt performed by fully professional actors (for the most part) so its a simple bit of fun and should really be reviewed as such.
I do however, have on MAJOR bugbear with it and that is that they missed a huge opportunity,
I would change the ending such that the scene with Grohl strangling his manager would see him physically transform into the devil, rather than merely being possessed.
The devil, now newly arrived on earth would set off to sow the end of humanity. On his way down a long and lonesome road (toward whatever mischief he had planned) he would happen upon 2 hitchhikers.
Confident in his recent victory over the foo fighters he'd taunt the 2 hitchhikers with the challenge "Play the best song in the world, or I'll eat your souls..."
After a moments pause the hitchhikers would look at each other and say "okay". They would then proceed to bamboozle the Devil with the best song in the world, confusing him with mathematical conundrums such as if one and one make two, what does two and one make?
Shaken by all this and not expecting to actually hear the greatest song in the world, the Devil would whip-crack his whippy tail and fall defeated to the floor!
Both amazed and confused, the Devil would enquire "be you angels?" to which the hitchhikers would reply "We are but men".
With this the Devil would be returned to Hell and the hitchhikers would proceed on their journey, pausing to pick up a guitar pick the Devil had dropped.
Sadly, the hikers were so overjoyed to have defeated the Devil they totally forgot the tune and lyrics to the song they had just performed.
... Roll credits