super .fi 3
Great headphones. That said, the bass is a little lacking. I listen to a lot of low stuff (classical, bass trombone, jazz, etc) and so the bottom drops out in the really loud stuff. They take a little getting used to for comfort, but for the noise isolation (27dB) it's worth it for me. i'de buy them again if given the choice over others. another plus is that the cord is replaceable, so if you damage your cords frequently (like me) you don't have to buy new headphones everytime!

A very good in-ear phone
I've had the super.fi 3 Studio for about a year now and for the most part, it's an very good in-ear headphone.

PROS:

1. Flat-out excellent clarity of midrange and treble frequency ranges. This is especially true of synthesizer music.
2. Superb efficiency--you can plug it into the headphone output of most portable music players and get surprisingly strong volume without the need to turn up the player's volume controls. I confirmed by trying the super.fi 3 Studio on my 3G iPod nano and my older Creative ZEN Nano Plus portable music player.

CONS:

1. The deep bass is bit lacking, but this may be due to the limitation of the headphone's single-armature driver configuration.
2. It is very tricky to get a proper seal of the headphone and the ear canal for best sound quality. You will have to experiment quite a lot with the different eartips provided with the headphone to find out which one works the best (I had the best luck with the large size silicon eartips). You can get custom-fit eartips from a third-party manufacturer for the very best quality, but be aware such eartips cost as much as the headphone itself plus the cost of going to a ear doctor to make the mold for the custom eartip.

Great sound
My previous headphones were not of the in-ear type, and I was a bit reluctant to make the step. I prefer the over the ear larger headphones. But it is a bit silly to sit with large headphones behind my desk.
But a solution was needed. Too much office noise: people on the phone, the coffee machine etc.
I surfed the internet and found that these ones were supposed to give good sound for the money, so I ordered them.

They give indeed good sound. I can imagine it is quite possible to buy even better ones, more clarity, more balance between the lows and highs, but these ones are more than OK. Far more detail than many low end ones. Never tried higher end.
When I used the lower end, I was aware that something was missing. I do not have that feeling now.

A reset of my ipod volume was needed. I now use the lowest possible volume level when at work, in the train somewhat higher.

At first I was (pleasantly) surprised how well they block outside sounds. In holland the bike is a often used form of transportation, and hearing the noises around you can be important. Do not wear these (or any other in-ear buds I assume) when participating in traffic.

The fit for me is good, although I can imagine that fitting them in "special" ears can be troublesome.

Packaging is nice. I could have done without the small box, or with the optional winder. One without the other does not make much sense.

So Very Disappointed
I was very disappointed when I received these headphones. I have owned sony in ear phones, as well as shure e2c's. I was attracted due to the reviews, however I did not realize that these would be seriously lacking any bass whatsoever - so much so that the music sounds flat and stale. The sound reproduction creates a fairly wide sound stage, but the lack of bass is simply inexcusable. Even the Shure's, which are notorious for having a weak bass response had significantly more bass. I am not one who likes a rumble in the ear, or even an overcompensated bass, but this is just awful. The low end is so ill compensated that when you listen to a song with a moderate bass track, the music becomes distorted as if the bass guitar has been turned into static thumps in your ear. An to the nay-sayers, they ARE in my ears properly. In short, if you listen to podcasts or voices, these are great. However, even classical music comes across poorly. I had my hopes up for these!!

Excellent choice for the money
These are a replacemnt for the Shure e3c headphones I had. Reviews I read gave the ultimate ears a good alternative to the pricey Shure headphones. The sound in one of the Shure phones was crackling and decided to get new ones. With the ultimate ears, you can replace the wire, which is a better alternative than buying new headphones!