Pros: Sound is clear and crisp, great sub-bass response
Cons: Cable is not the best
Bought these two months ago, and they are my favorite IEM to date. One thing to note is that I did indeed get the condensation problem. It has only happened a handful of times, and has completely cured up, but it is something to be aware of. I had to dock a half star from the Design rating because of this issue. They're still my favorite IEMs, though. I might have some funny ear canals too, as most people never got the problem.
For me, personally, these trump the GR07, SE215, and MC5/3/2. I always recommend that you do your own testing. For example, many people may find the GR07 to be on par or slightly better, whereas I found the EPH-100 to be much better. I'm chalking it up to my ear canals. More (rambling) thoughts here: http://www.head-fi.org/t/577712/yamaha-eph-100/3030.
From a review I also wrote on the Yamaha site:
Some excerpts from my rambling:
First, the comparison against the GR07:
The guitar in "Collide" sounds muffled or dampened on the GR07. Similar effect in "Under My Bed" by Meiko - the intro sounds much clearer on the Yams. The guitar intro in Michelle Branch's "Breathe" is markedly cleaner on the Yams. And when the vocal lines come in, they again sound sharper on the Yams. So on and so forth for other songs. After adding in my EP-630 into the testing, the GR07 is not as noticeably clearer than the EP-630 as the EPH is. Especially for The Duhk's "The Wagoner's Lad", which I have in .flac, the EPH is by far the sharpest, followed by the GR07, and then finally the EP-630.
Did another long A/Bing session today, and the Yams are the clear winner. Retested "Collide" and "Cosas Que Suenan A..." numerous times, which really showed how much better guitars sound on the Yams. I also A/Bed the Feed Me remix of Robyn's "Call Your Girlfriend." The Yams again sounded clearer, this time on both the snares and the electronic synth notes. I felt the sub-bass was better on the Yams as well - when the bass line comes in I get a much more visceral feeling when I'm wearing the Yams. I also A/Bed the instrumental version of Radiohead's "High & Dry", and the guitar is more clear and crisp on the Yams.
And another excerpt of some of my thoughts of the EPH-100 against a pretty hyped up product, the Sony MH1C:
The EPH-100s sound clearer than the MH1Cs. From the songs I've A/Bed so far, guitars and vocals sound slightly better on the Yams and there seems to be a sense of overall improved clarity on the Yams. When a slew of instruments enter the mix ("Por El Miedo A Equivocarnos", ~35 sec in and ~2:40 in; "Entertain The Pain", ~50 sec in) however, the difference becomes much more noticeable. The MH1Cs become congested while the Yams keep everything separated and clear. In addition, the Yams are less fatiguing, which I noticed after many, many repeats of sections of several songs, over and over. The MH1Cs sound harsher ("Por El Miedo A Equivocarnos" ~2:40 in, especially) and its inability to keep all the instruments from running over each other contributes a bit to this as well.
Only two cons. First, I got this condensation problem after extended periods of listening (maybe >5 hours or so), which would dampen one side of the earphones. This problem has only happened a handful of times, and has always resolved itself by simple drying. I'm listening to the EPH-100 right now, and loving it. This not a dealbreaker at all (especially since most people never get this problem, I think I have slightly wonky ear canals, but that's another story), and even considering this I put the Yams above the GR07, Shure SE215, and the Mtymotic MC2/3/5.
The second con is barely worth a mention, but it's that the cable is not amazing. The GR07 has undoubtedly a better cable. The MH1C, on the other hand, has a godawful cable. The Yams' cables have never bothered me - I never even thought of them as a con, until some other people pointed it out and I thought, "Hum, I guess the cable's not the best."
At the end of the day, these IEMs are absolutely phenomenal, and I'd buy them again in a heartbeat (I'm actually considering buying a 2nd pair of these for working out. I bought the GR07 for that purpose, but the sound was so much worse than the EPH-100's I had to return them. Probably something to do with my ear canals that don't play nice with the GR07. Alright sorry, I'm rambling off now.).