I FINALLY received my ZS5 after waiting over 40 days, having ordered during the pre-order phase.
I will post a more thorough review after a bit more use, but my initial impressions are very positive, they do sounds pretty damn good, and I was lucky enough to get the "premium" box with magnetic lid and 6 pairs of tips. Nice.
Quick summary.
Sound:
Great sound overall, wide soundstage, high energy treble without sibilance, good instrument separation, nice tight bass, I'm not noticing bass bloat like others have reported. I have noticed a dip around the 6k range, which is where vocals are at, making them recede into the mix just a bit. I've pushed up this frequency with EQ quite significantly and it comes out sounding really great.
I've only tested with my Sony Z5, need to get it plugged into my AudioGD for some critical listening. But having used them for a couple days on my daily commute, they sound very very good.
Build quality:
The cable. Oh boy... why would they make a rubberized cable? It's predictably sticky, which means it will be more prone to tangling and snagging on clothing. It's not terrible, but it's a curious choice. I don't understand why they would use this material. I did order the silver cable additionally, which is very soft, comfortable and feels great.
That said, the microphone and control toggle feels fantastic, it's made of metal and the buttons have a nice tactile click. These are important factors for me since I listen when I cycle or commute and need to change tracks frequently. Very nice buttons with a premium feel.
The memory wire is not too bad for me, I don't have any problems with comfort. Though I do find the 'star' nozzle tips are too hard and uncomfortable, so I'm using the other softer ones.
Improvements:
The sound is great for the price, I'm very happy in that department, where I think KZ really need to improve their game is in their attention to detail in the overall package. They could easily make these an absolute killer by doing the following: spend less on premium packaging, put that money into including the silver cable as default WITH microphone and controls (why can't I get the silver with controls!?). Forget about those star tips, they suck, include fake comply foam tips in addition to the silicone ones. And boom, just like that you've got an absolutely savage killer of an IEM.