From the moment I put these on, I knew it was money well spent. I enjoy listening to music again, I hear things I've been missing with other ear buds. My wife said that when I first put these on and heard music that a smile spread across my face. I use these mostly at work and wear these for at least 2 hours a day, but probably average around 4 hours a day, with no fatigue or pain.
I went from OEM headphones to Bose in-ear to UM2RC. The difference between the OEM headphones to the Bose was only a slight increase in sound quality, the sound was muddy. So I was expecting some better sound but the difference in sound the UM2RC produces is magnitudes better than what I was expecting/hoping. I won't attempt to describe the sound because I lack the knowledge and I'm not an audiophile, but I will say that these have spoiled me and I can't imagine anything sounding much better.
I only have 3 minor complaints. One, they're a slight hassle to get out, because I'm in an office, people come and talk and it takes a couple of seconds for me to pull them out, and I have to ask people to repeat what they were saying, but I am getting faster at removing them. Two, when people ask me about them I'm not sure on the pronunciation, is it West-one, or is it Wes-Tone? Three, I wish they had slightly more punch to the bass out of the box, but the bass is tight and doesn't interfere with the other sounds.

I am very pleased with the UM2 RC in ear monitors. We have used in ear monitors for most everyone in our rock-styled church band for quite a while, but the bass guitar was one of the last areas because we were concerned that we would need some type of vibration feedback to suppliment the in ear solution (butt-kicker, etc). I am happy to say that we were wrong. All you need for any band location (including bass) is some UM2 RC in ear monitors and you can start using your wedges for boat anchors or whatever because you will not want or need them on stage any longer :-)

Very good sound. I had a pair of Bose before but Westone UM2 definitely sounds better. Although I think part of the reason is that the UM2 has very good sound isolation (Bose did not). Overall, good bang for the buck.

I bought these late summer based on reviews on this website. Earphone Solutions was extremely helpful and provided superb service delivering my earphones. I have used these on business travel and the gym. As the other review states, these have amazing clarity and definition - WHEN THEY WORK! I purchased these because having replaceable cables eliminates the usual issues with overused cables breaking. But that said, the connectors are very cheap. They wiggle out very easily. For the money I paid I am very disappointed as I should have waited for the Shure 425 or paid the extra money for the Westone 3s. Beware!

I started using my new UM2s on Monday, October 18. I have used them everyday at the gym for one and a half to two hours per day. The sound is awesome, better than the Shure EC5s that I also own. I have had an ongoing problem with my UM2s though that is really annoying. The sound goes in and out, particularly in the left ear. At times I have no at all sound coming out of the left ear bud, other times it comes and goes intermittently. The problem appears to be with the removable cables because if I jiggle the cable connection to the ear bud when I'm having problems the sound comes on, i.e., the problem goes away. I have never removed the cables from the ear buds, they were already inserted when I opened the box. Whenever I have a sound problem, I put pressure on the connection between the ear bud and the cables to tighten it. That usually solves the problem temporarily. I always ensure that the cables are securely connected to the ear buds before I put them on. So far the UM2s play fabulously initially, but after an hour or so of cardio, the sound begins to comes and go. I am resisting sending my UM2s to Westone for warranty repair, but if my listening experience next week is the same as this week, I will reluctantly do so.