I just received my pair, first impression out of the box was that they fit the ear very well and seem to sit securely. They seem sturdily built, more solid than the pictures had me thinking. I quite like the very soft tips they give you and I am using the blue ones, I'd assume that these softer tips have a lesser chance to hurt the ear than the very stiff ones Truthear give you.
Out of the box I found the treble to be rather... tinny? The treble felt overpowering to the point it hurt to listen to, and they didn't have enough bass which probably helped make the tonality even brighter. While the treble was piercing, I was happy to note that I didn't hear any sibilance.
Gosh, I don't really like trying to describe IEMs and headphones as it just sounds like typical audiofile junk-lingo.
So, I loaded up Oratorys Harman EQ and while that sounded better they were still much too bright. I am still toying with the high shelf treble filters Oratory provides in his EQ, but currently I am ~5db below the Harman pinna gain and that sounds rather neutral to me. But I am not too happy with the bass still, because while it's full but it seems to lack the impact of my other IEMs, the other-other Zero and the Hexa. Using a sine sweep they sound the same in the sub-bass region, but with music I simply notice the impact of lower notes less with this set. Who knows, it might be that I am hearing differences that aren't really there - it does take a while to change both the IEMs and the EQ and my memory might already be wrong by the time I am ready to listen again.
Overall, these things are 20 bucks. If you have EQ available and you are fine with putting things in your ear, they are a no brainer IMO. I definitely prefer them to the ASR darling, the TCZ, as those are simply huge in comparison to the 7Hz Zero. The smaller size would probably mean they have a higher chance of fitting in the ear of more people.