The old logo also looked far more professional and serious, which is exactly what you want if you're setting yourself up as a serious alternative to Google and Chrome.

They already had a tough time becoming known, with this logo that doesn't link well to Mozilla this is becoming even harder. If you took a random person and asked them who the new logo was for, they wouldn't know. With the Moz://a logo, they could easily figure it out.

The chosen colours are also too harsh. The activists/hackers/whatever already likely use Firefox. It's exactly the pond they shouldn't be fishing in. They should focus on a brand messaging that demonstrates reliability, performance and ease-of-use, being the choice for the casual user. Because that's the market they need to win.