Pros: Sound Quality (Post Burn-In), Portable device compatibility, Lightweight
Cons: Feels INCREDIBLY plasticy, Maybe too light, Soundstage isn't the best, Isolation
Disclaimer: My review may be rather invalid due to my lack of experience in the audio world. In that case, if you are new to this, it may be very helpful.
The HD 439 was definitely a good buy for its purpose of being my iPod's go to for music.
The sound is great for the price. Very crisp at the mids to highs, and the bass wasn't overpowering.
The soundstage however, was a slight let down, being kinda too narrow to enjoy some more closed-off' sounding songs
The build quality is terrible, but expected for the price.
They are made of a cheap, lightweight plastic that does not feel durable at all (So little that I feel worried taking them in a bag due to possible breakage)
Comfort wise, these things are good. They are too light to be a burden, but maybe so much that moving around quickly may make them fall off.
Additionally, my ears (not that big) don't fit perfectly in the headset. This, along with the diagonal circum-aural earcup design means the headband feels like it is leaning forward.
The isolation isn't very good. Even for closed back. Any comfortably loud volume that is enough to drown out other noises can be heard by anyone nearby, though not extremely clearly.
Think about that before buying.
If you have any lower quality mp3's, this will gladly identify them. The HD 439 make it very obvious when a low bitrate is apparent.
The replaceable cable[s] (1.4 and 3 metres I think) are kinda tricky to remove at first, but not too difficult. The replaceable part is great if you break one though.
Summary - TLDR
If you are looking for a decent pair of headphones, that wont break the bank, are expendable and for use with a portable device (iPod for example), these are likely the ones to get. If you are looking for A+ quality in every field, you may want to look somewhere else. All in all these headphones do their job as a great set of cans to take places where you could break or lose them, due to them being rather cheap and still decent.
If you can afford better for at home use only, DON'T bother with these. Go look at some 558's or something.