After playing around with the Mojo for about two months - in a variety of setups, with different headphones - I have come to what is likely to be my final opinion of it.
Good:
1) It is an amazing DAC, truly as good as it gets for a portable. To my ears the resolution, level of detail and instrument separation are simply perfect.
Bad.
1) The amp section is so and so with Shure 535s and Sennheiser IE800s, but downright awful with JH Audio Laylas. Soundstage is narrow and round. Also, don't expect it to drive picky planar magnetics like the Hifiman he-560.
2) The battery life is short and will always make it a hassle to use.
So, in conclusion, the DAC is a miracle but the amp is overrated. Personally, I will be on the lookout for an amp and a carrier. The amp needs to be good with Laylas - thinking of Pure 2 and headstage arrow - and the carrier slimmer and more modern than the awful slow and clunky old ak100 people are paring the Mojo with (because they fit).