First of all, I'm giving 5 star to the "sound" considering that we're talking about a ~30€ headphones.
So, for what you spend on this, I have to say that it's probably one of the best options: I tried AKG K-52 and I was pretty not satisfied with the sound-quality, so I changed for this Superlux, totally worth it.
Whatch it: unfortunately it lacks - heavily more or less - on isolation; it's closed-back ofc but it does not provide a safe isolation for tracking etc.
More on the negative sides: it's quite unconfortable. Personally, I cannot wear this more than 30 minutes.
The quality of materials is not the best one, but I have to say that is pretty reasonable for 30€ headphones, on the plug side it' pretty annoying but one could have easy time soldering it if you do that.
Overall, not the best headphones ever but it's more than OK if one needs a cheap pair of headphones for everyday use or so.