Just picked up one of these in my search for a neutral closed-back headphone. Amazon had a very good price, plus I had some Amazon cash-back to burn.
Thus far, they are pretty much as described. Good construction. A bit heavy, but not bothersome due to good padding and design.
Bass is a tad light on quantity, but the quality is there. Mids are good. Treble is a little emphasized, but never shrill/sibilant, definitely not as bright as in Beyerdynamics (e.g., DT1990, which is even supposed to be one of the Beyers with the most tame treble). Detail retrieval is very good. I'm using the velour pads for now. Driving it out of a Schiit Jotunheim (DAC and amp).
The Pioneer SEM-5 is a really interesting headphone and it's too bad it doesn't get more exposure. Some very mixed reviews on various forums, although most web published reviews seem positive. Ether C Flow is on the way, so we'll see how the Pioneers compare. Ether C Flow seems to have very mixed reviews with some people claiming they are deeply flawed, and others saying they are the undisputed end-game closed headphone.