Pros: build quality, distortion free sound, no sibilance, decent soundstage
Cons: a bit too bass heavy, mids/vocals sound veiled, J-cord is a PITA
So these are the FOTM, but for good reason. For 30 bucks, you get a fatigue free, dynamic sounding IEM. The soundstage is decent for this price bracket, instrument separation is good, sub bass extension is quite insane and they are built extremely well.
Should everyone ditch their $100+ IEMs for these? No, they aren't better than the other IEMs I have heard that cost $100+ because they lack the precision in instrument separation and instrument placement. The mid-range is also quite dark and not that well extended compared to higher priced IEMs. Contrary to another review, these do not sound better than the Yamaha EPH-100, and that margin isn't that close either.
BUT, there might not be a better $30 IEM out there in overall sound quality and fun. If you want analytical for cheap, you should steer clear from these and go with the VERY good RE0 for $50 instead. If you want a heavier bass presence, and more laid back mids/highs, this is a great choice.