Summary: After buying around a half-dozen closed "studio" monitors for use at home (not in the studio), I finally got around to getting the DT 250. It will be the last one I buy, because it is perfect. The bass is nice and strong without being overwhelming, the upper frequencies are nicely detailed and clear, it has great timing and is very musical, and it is comfortable.
Summary: I use them for listening to music on my PC without disturbing others. They are pretty neutral with a slightly recessed treble. The bass is pretty tight and punchy. The only thing I don't like so much about these headphones is the clamping force on the head. They are a lot tighter that DT770 and DT880. Overall though it's a very enjoyable headphone.
Pros: Clear Sound, Easy To Use, Powerful, Professional Functions, Versatile
Summary: These DT-250 (80 ohm) are just flat-out the best sub-$500 headphones I've yet heard. I found the Shure SRH840s way too bright, and returned my DT770s for being too dark.
The soundstage is as wide as you could hope for with closed-back cans. Separation is really great, and I find them to be analytical enough to reveal all the detail I care to hear, without turning suboptimal recordings (or encodings) into garbage.
Summary: I own the 80Ohm model, do note that the 250Ohm model should sound very different.
Looks: You'll look like you're working for the sound crew of a broadcast company.
Construction: Solid materials used through out. Some weak points where the headphone and cups meet. Here's the kicker, though: All parts including the head band, driver and cable can be ordered as spare parts.
Pros: Potentially excellent sound(250Ohm), comfort, modular construction