Pros: Great customer service (in US from Stephen), great sound, BASS, but the mids and highs still come through, and they arrived a month early
Cons: They're pricey, but not out of line with other customs. So that's like half a con.
Alright, I told the good folks at Unique Melody that I would provide my impressions. I think that I've had them long enough now, and used them from enough sources, to give some feedback.
Thus far I've used them straight out of a Nexus 10, a Galaxy S4, the S4 > E18, my computer > E18, a Clip+ (Rockboxed), a Fuze+ (Rockboxed), and a Sony ZX1. I've flown with them, I've ridden public transportation with them. And I use them at work just about every day. And I absolutely love them. The bass is definitely forward, which they make very clear. You don't buy the Merlin if you want a neutral sound signature, Unique Melody offers other choices for that. This was my first venture in to CIEMs, and it was the most I'd ever spent on headphones/in-ears. I was using HiFiMan RE-262s before I got these. I love those little guys, but these just go so far to blow them out of the water, that I haven't used them since the Merlins arrived. Actually, I gave them to my girlfriend since they weren't getting any use.
The order processing is simple, and it took far less time than quoted to get them to me. They also fit perfectly on the first attempt. They're just so comfortable. The only time they give me issues is when I'm at work, and people walk up to me repeatedly. Some days I can't just get left alone to work, and the removal process does irritate my left ear (not my right, just the left, who knows why) if I do it over and over. One thing that I will note is that during the order process, when you're selecting graphics, they aren't accurately reflected on the site that simulates what you're going to get. I put my alma mater's Block M on mine, and it showed it like it was on the outside, stuck or painted on. But that's not how they came, they're under a layer of the translucent material, making them not really standout at all:
That's not a complaint, I should have asked. Because, next nice thing about ordering here in the United States, Stephen Guo (even when you spell his name Stepheh on your first correspondence, he won't even call you out for being a jerk) is really easy to work with, and answers any questions you might have. Don't make assumptions, just ask. They'll guide you through the process. Also of note, I got them delivered in half the quoted time, which was great.
Back to the sound, in a word: marvelous. Detailed and punchy. It's definitely a warm and musical sound signature. They even have a decently large soundstage. Not as wide as my Q701s, or my HE-400s, but wider than on any other in-ear I've heard. With the ZX1 (pictured with the Merlins above and below) they have a wider soundstage than I ever expected from in-ears. And on tracks with, for example, a standup bass, you can feel the strumming, it's a rather remarkable experience. And honestly, I expected that they would be an issue to pair with a player, and they really haven't been. Of course, I've never tried them with anything that has an absurdly high output impedance like my HiFiMan 602.
I know that this is a short impression. But seriously, if you're on the fence (like I was for months) just order them. You will not regret it once.