Just playing mine for more or less 4 hours. Initial impression is that i am so impressed with the micro detail IE800 can reproduce. It is amazingly good.
The Bass - this is the thing that surely can make you go oooomph...!! very delicious bass. It is solid, meaty, impactful and you can definitely feel the punch ! i am talking a kind of bass in bass-head territory (if u like to say so) but with audiophile quality. Very nice textured.
The mids - this is where my cons laid on IE800. The mids is GOOD. Very rich resolution but for my taste i need just a tad more forward and lush. The mids does not have that kind of lust feeling to it, but the resolution is quite good. Everything is very clear. But i may prefer something more lush so is more enjoyable for jazz or vocal songs. The upper mids has a bit of edgy. Is not so natural. But i can live with that. Still pretty good for me. Remember...even though the mids is not that thicker and lusher...but i can tell i blown away by how good the instrument played on this thing with jazz or blues songs. The strings of the guitar, trumpet, saxophone is excellent sounding !
The highs - is very smooth and crystal clear. It can be too sparkling for some...but none of sibilant that i could fine so far. everything is just smooth sounding.
Overall...i am VERY happy with this IE800
NB: I would not compare this with my SM3/SM64/Shure 535red, because i believe IE800 is not at the same level...is higher of course !