The DTX501p has very good bass like a larger headphone, it has rolled off highs that can be mostly compensated with simple EQ, and it has some uneven response between 1 khz and 3.5 khz - 2 significant peaks and one significant recession. It's the most comfortable on-ear I've used, comes with an ideal small carrycase, and has a decent single-sided non-detachable cord. Build is just average, but it looks good enough to last if not abused.

Edit 9.9.2011: Isolation is average for a closed on-ear, which seems good to me. Leakage is minimal and this should work OK in office cubicles etc.