The sensitivity to the telephone network is not as good as my previous Samsung Nexus S or the excellent HTC HD2 (from this point of view). I have not tested the 4G.
The big disappointment is the gateway to KitKat, which poses serious problems. some applications have become incompatible (S View S Cover, Call Recorder, etc.), pictures are less good, and connecting to Bluetooth devices can cause problems as some forums. Conclusion: Stay Jelly Bean and disable automatic updating.