I recently got the A151P 2nd Gen and I wanted to share my thoughts on them. I got them from Massdrop on promotion and was initially a little disappointed at the what I saw.
However, once I plugged this in and listed to them, I had a little grin on my face. The bass was abundant, punchy and clean. The mids and highs were not affected and were both prominent without sibilance. Those who are criticising the bass either like a LOT of it or haven't achieved the right fit. I was fortunate to have the medium ear tips fit well; others I tried degraded the sound.
The one criticism I have is that the build quality can be further improved. I know these are $25 (initially $50~80) but we need to expect more from manufactures even at this price point. The sound quality needs to be matched with materials and a build that will last the test of time. Only then will this truly be a value set. An example of this is the poor of strain relieve on cable waiting to come loose.