Overall, I really liked the way these guys sound, and you'll immediately notice the heavy level of detail. These earphones are very clear, and they emphasize the full range--from the bass to midrange through the treble--but treble is accentuated the most.
One of the attributes of good headphones is that the sound doesn't seem stuck inside your head and feels more "open." Listening to some ambient Brian Eno, for instance, that openness came across--these guys are very open for in-ear headphones.
Bass is really good, but it's worth noting that there's so much treble that sometimes it draws your attention away from the bass. It depends on the recording and how it's mixed, but these are very precise, fast-sounding headphones; they aren't laid-back.
A lot of the times when you have more aggressive sound, it can get a little grating, but these weren't harsh in any way, though I advise listeners who are sensitive to accentuated treble to shy away.
Depending on how you look at it, the unique design of Monster's Miles Davis Trumpet earphones will either be a big selling point or a deal breaker. I liked their design and got a lot comments about it (yes, these will attract some attention). That said, I didn't find the earphones incredibly comfortable on the go and I'm not sure if I would use these on an everyday basis to travel to and from work in New York City (on the subway) or in more active situations.
But aside from those "mobility" drawbacks, they sound good enough to have you itching to relisten to your music collection and hear just how all your stuff sounds through the Trumpets. That's a good thing.