Played with them some more. The midrange is actually nice. Female vocals sound pretty good. I EQ'ed the bass at 50Hz down by 5dB and they sound half decent. Shame the iPhone can't offer that level of EQ (though I'm not a fan of using EQ in the first place).
I'll be riding the bus home with them, so I'll have a chance to try them portably. Maybe that's when they'll show their strength.