Pros: foam tips, nice cable/durability, sound
Cons: driver flex with silicone tips
Before I start, I am no audiophile and have very, very limited experience with good headphones/earphones. This review is more of just my impressions as someone with almost nothing better to compare it with.
I got this for less than £10, which was an amazing steal, considering how good they are. The packaging is nothing special, just typical retail type mostly-transparent small plastic box. Mine came with foam tips already on the earphones, and the rest of the silicone tips (just s,m,l single tips) in a separate bit of the box. Design wise they look pretty cool, mine are black with a small amount of red which works quite nicely. The earphone shape is similar to the RE400 I think, and is pretty small, but depending on how deep you insert, the back end of the "barrel" can rub against the edge of my ear (though this can be fixed by inserting it deeper). I'd never used foam tips before, so it's awesome that you get a pair free with these (especially awesome considering the price of a pack of 3 pairs of foam tips costs £15...), and I'll never go back to silicone tips. The little bit of time spent fiddling with them to compress and insert well is worth it for the comfort and seal. the cable is very nice, it's actually very tangle resistant and nice and smooth. There is a great strain relief on the plug, and decent strain relief on the ear pieces and y-split. I have no doubt this will last a very long time.
The sound, like I expected, is pretty neutral. All I have to compare these with is my Superlux 681-EVO - the EVO cost about double these earphones, at roughly £21. Honestly I feel like the delta is a bit more accurate, specifically with mids. It just sounds so much better than I expected, and is perfect with my clip+. The 681 evo obviously has a wider soundstage, and has more of a "big" sound. The bass goes a bit deeper and has a bit more rumble and seperation than the delta, but the delta still has good impact and accuracy.
I can't really comment on a lot else sound-wise since I have so little experience it would all be wrong and misleading to people reading this review. I find myself sometimes switching from my 681 evo to the deltas when I get tired of having big plastic-y headphones on my head, and I do prefer certain genres of music with them (Folk stuff, with lots of vocals. Angel olsen for example, sounds better in my deltas.)
The deltas retail for closer to £12 or £15, instead of the £9 I got mine open-box for, but that is still definitely worth it and I would 100% recommend these to anyone wanting good cheap earphones.