Pros: Great bass / Not too expensive
Cons: Pleather pads / Looong straigt fixed cable (I prefer removeable or coiled cables)
For their price they are probably one of the best basshead cans out there. While I find my Beyer 770 Pros sound overall somewhat more "refined" the HFi580s clearly beat em in bass rendition...
Comfort / Build Quality:
I'm not a big fan of pleather pads as they tend to get hot and sticky when its warm, but besides this they are not too bad. Overall build fits the price-point imo.
My recommendation is to compare em with the Beyer 770 Pro 80 to check where your preference goes. If you like bass and don't want to spend too much, both are a good choice, in the end it's just a matter of taste imo.