My experience with headphones are very limited. I have only tried a few closed headphones. Going from memory like senns momentums, vmoda100, custom one pro, m50x, I can tell you I was more impressed with these dolphins. I liked the momentums the most out of those but Peter was right the dolphins do have better soundstage than momentums and better bass quality. Now the dolphins do not have the soundstage as wide as my hd598 but considering they are closed they do pretty well. It doesn't sound congested.
I will be brief:
Bass: For me since I have been very used to my ckr9s sort of bass I'd say its slightly lacking here in the low department. However it is enjoyable enough for pleasure listening. Its fast, accurate and gives a satisfying thump (not tunderous) but I'd prefer the bass fto have a little more extension and deepness in attack and more reverberation. The subbass is lacking if I compare them directly to my ckr9s. They almost not rumble at all. However with the bass this fast, it does not bleed into the mids and here is where the mids shine.
Mids: The mids are awesome. Very good detail retrievals and clarity. Not as forward as my ckr9s but they sound very enjoyable. Vocals are organic enough for my liking better than the ones I said I tried.
Highs: The highs are crisply detailed and smoothly extensive. Drums sound realistic and natural. I can hear more presence from cymbals but they are not in anyway sibilant to me.
All in all its a damn good phone for $99. Though it may not feel like the most of solid phones in terms of build quality but it does hold up well and light. Good for portability.