It was disappointly dull to start, and average in the end. Nowhere near as funny as Blame Society's Star Wars riff, and as I recall, not as funny as Rifftrax's Star Wars riff either. I laughed out loud a good dozen or so times, but the rest of the jokes were too obscure, obvious, random, hateful or sardonic for me. I felt almost no contribution from Blame Society, but that was expected, as the joy of their riff was in the surprise of how good they were, and the freshness of their own personal riffing style, neither of which comes through with the regular riffers.
The riff wasn't twice as good for the collaboration, and I'm hugely let down that we got this mish-mash instead of two separate riffs. If it's for the selling point, Chad Vader was enough without Matt and Aaron writing.