10.2 was terrible for me, no echo and no call drops, but often people said they have troubles to hear me, often I had messages that someone tried to call me and I was not accessible, later I found out that indeed I can't call myself from other phone. Data connections were poor. Maybe this can work in other countries, but here in Poland it was unusable
Now I'm on latest weekly.eu ROM, it's much better - people can hear me and I'm rather online, but I still have some issues regarding quality - one call was dropped, once I could hear every second sentence. Still it's just faulty but seems to be better than that from stable. I still hope they will fix that!
Phurya: I expect that it may work better in different countries, some carriers support different technologies. I never had issues you described like echo, but I had other problems. BTW: is VoLTE working on your side?