When you go see your kid in a school play, you don't compare their performance to McKellen in Godot.
John Carter wasn't great, I mean, I liked it, but, generally it didn't go down well, this film has 0.00006% of the budget, and to me, a military engineer and Sci-fi nut, it managed at least 10% the entertainment value. If you want to be negative about it, (and John carter), give JC 1 star, and this film still deserves 10 by weighted comparison.
The action is well paced, the costumes are...brave? and the tongue-in-cheek campness of it all is hilarious, there's even the odd homage.
Given a few hundered grand to pay for an acting coach, wardrobe and a couple of experienced AD's, I think this team could easily produce something comparable to, say, The Ice Pirates.