Well, it depends, because the Samsung GS4 is rumored to be out, or at least announced, around April. So, while the N4 is a great phone with the pure Android experience, there might be better options on the horizon. Keep in mind though, if you are always waiting for the next big thing, all you'll ever be doing is waiting.
I guess my thought on going with the nexus was that I can get it for 350 without having to use my upgrade. There isn't a new Nexus on the immediate horizon (next 5 or 6 months) is there?