I just purchased a pair of these headphones in the 80 ohm version as opposed to the 250 ohm model listed under this header. The two are similar products used for different applications but like any audio product you have to hear them for yourself.
Despite the subjectivity disclaimer, I will say these cans have a seemingly more flat response compared to the Sennheiser HD280 and the Sony MDR7506 I auditioned side-by-side in the store. The mid-range response of the dt770's was the best quality- because you can actually pick out the mids. The high frequency response was articlate without being pushy, a big factor for me. In contrast, the Sony phones seem to feature an aggressive and unrefined response in the high frequency. Otherwise the Sonys are fine for $100. The Sennheisers (also $100) seem to isolate better than both the Beyers and the Sonys, but I found the Beyers the most comfortable of the three. I don't have big ears, but the Sonys seem to have little chiclet ear cups and isolated the least of the three. The Senns are definitely worth the $100, but I can't figure out why the Sonys are audio industry standard headphones with that almost prickly high pitch response.
I picked the Beyers even though they cost twice as much as the other two because of the exceptionally even response I got from them. When I took them home I tried them out on every little lo-fi device I could find, and they continually made me shiver with their fidelity and overall tempered sound. Do you want to 'hear' your headphones influencing the music? I don't.
The Beyer's base response was hearty, maybe due to lightweight transducers that reproduce sound more efficiently than most cans. But for me it was hearing the mids, a range that humans don't pick up as easily as bass or high pitch sounds, that made these worthwhile. If you want super high quality phones, pick these up.