There have been a few posts critical of this review. To my untrained ear, the review follows the pattern of most reviews, both in media and by happy campers on this thread.
He characterizes the sound using the same mix of terms (sound stage, separation, bass, mid-range, bright, soft, etc.), compares it to two other amps, it's older sibling and another significantly more expensive, and an array of headphones at different price points and styles and with variety of music.
Unless you go all ASR on it, what else is there.
It was unfortunate that he chose to do the comparisons, apparently exclusively, using the internal DAC's instead of using a consistent analog source. In the end we don't know if it's the multibit card or the amp itself that sets it apart. Something he acknowledges but does nothing about.
I'm not defending or criticizing the review, or Mr. Guttenberg, in general but I wonder what folks want or expect, more than what was in the review.
Of course, the best review is
Jason's product announcement chapter!