In all 3 major connectivity parts (cellular, Wi-Fi, Bluetooth) the Nexus 5 has the most powerful modems I have experienced on mobile devices so far. They are F-A-S-T and extremely agile. I do not know whether this is a common feature of S800 (probably it is), or how well the new Apple stuff do in this area, but the way the Nexus 5 handles various connections is swift and graceful. Of course, the addition of LTE is perhaps the most significant upgrade over the Nexus 4, even disregarding its performance.
For some perspective, here's a comparison of the Nexus 5 with the Moto X:
http://www.androidcentral.com/nexus-5-vs-moto-x
I tossed both the Nexus 5 and the Moto X on the charger until full, then set them on my desk, face down and didn't touch them for about two hours. This is the result.
Not only is the Nexus 5 awake at least twice as often as the Moto X, but with both phones using a T-Mobile SIM card, on the same account, on the same desk, the signal uses more juice to stay alive on the Nexus 5, as indicated by the yellow "Mobile network signal" bar.
Granted, the N5 is running 4.4 while the Moto X is running 4.2.2, so it'll be interesting to see if the same result happens when the T-Mobile 4.4 update completes its roll out.