All the reviews commenting on poor build quality and product failure are very relevant. It's hardly unusual for a product to have problems when first manufactured and then be improved, but it seems that the Nuforce EDC3s have all the same faults now as when they launched a couple of years ago. My EDC3s arrived with a faulty right side earpiece out of the box. Fortunately Massdrop's customer service and warranty is excellent and I received a replacement pair very promptly. The replacement pair works but I can't help wondering for how long.
Anyway, to comment on the working pair:
The comfort is excellent. These are a really snug and comfortable fit for me, very much like Shure SE series. The cables are fine in terms of length and lack of noise. I like that there is a sliding keeper as well as a velcro tidy. However on one side the earpiece has a good snug fit with the cable but on the other earpiece it is *amazingly* tight, being difficult to remove and terrifyingly difficult to fit, with bent pins always seeming likely.
The accessories are good. The small hard case is excellent, offering genuine convenience and protection. The foam ear tips are very good. It's good to have a cable with a mic/control button and another plain cable with a bit more length.
The sound is decent. The lack of bass that many people criticise is apparent. A flat bass response is good in a loudspeaker. In an IEM it is maybe reasonable in theory but pretty unsatisfying in practise. Live music and loudspeakers move air; the bass isn't just a tone, it's also a physical experience. Headphones, especially IEMs, can't do this so a small bass boost is a very good way to give the same impression. In my opinion the totally neutral and flat response is a mistake because it offers an unnatural experience. Fortunately the EDC3s are easily capable of benefiting from equalisation. I use a parametric EQ to give a Low Shelf 3 dB boost at 90 Hz with a Q factor of 0.7, and this restores a little bit of feel and there is zero added distortion. The rest of the frequency range needs no correction. Aside from the bass issue I feel that the EDC3s are very nice to listen with. They grow on you. They commit no crimes and offer a very detailed and enjoyable sound. I think the soundstage is fine. Probably this depends on how well matched the left and right side drivers are so I suspect the variety of impressions offered on this subject in other reviews says as much about Nuforce's quality control as anything else.
These are never going to sound rich and vibrant like a really good headphone or dynamic driver IEM, and I don't think they are quite as good as the (dual balanced armature) Shure SE425, but the Shures cost twice as much. The EDC3s are more easily driven to good volume levels by a smartphone than any other good quality headphone or IEM I've tried.
Assuming you get a pair that works and continues to work then I think the EDC3s are very good value, very easy to live with and a great buy. But I'd hesitate to recommend them due to the numerous complaints of defects, including my own experience of the same.