Exceptional detail, imaging and bass. Plain and simple I hear things with these that I do not hear from my ZSX10 Pro, TinT2, TinT3Pro and Tin P1 Planars. They are my daily...I keep trying the others and ALWAYS go back to the BLON 03.
Want a negative? The cable it comes with is pretty much trash so I highly recommend replacing that. But to be honest, it's a small price to pay...
I am a big fan of cheap audio that sounds good. Who wouldn't be?
I have a couple of sets of Tin T2s that I like, but they are a bit sterile for my tastes. Lately at work I've mostly been using some Koss KPH-30is, because once again cheap and good-sounding. I like the fact that they actually produce some bass but don't sound terrible when they do it.
Got the BLONs....oh wow. These are quite possibly my favorite-sounding things. The bass is way better than I expected, and I was expecting it to be pretty good. Treble is still there, and never shrill with no sibiliance. Probably a bit more emphasis on the bass than people who want a flat response would like, but I enjoy it. Gives good depth to everything without being overwhelming (or sounding terrible).
I haven't minded the cables as much as other people seem to. Sure you need two hands to put them in, but I can deal with that. I might try some foam tips a some point. Right now I'm using the largest of the silicone tips that they come with and getting a good seal and good sound, but they start to get a little bit uncomfortable after an hour or so. But every IEM does that for me, so don't judge them harshly by that measure.
I can't recommend these highly enough.