I'll be upgrading. GN to my wife, N4 to me. Upgrade for both of us! I do miss the HSPA+ 42mbps speeds I was getting on the GS2 before I switched to Nexus. I would average 12-15mbps. On the GNex HSPA+ 21mbps I only see about 5mbps or so, which is noticeably slower. Can't wait for the upgrade! More cores, better GPU, more RAM, faster network, better screen, way better camera, wireless charging.
Things I will miss: the curved screen (looks nice and keeps screen from scratching when faced down), headphone jack on bottom (easier placement for my car setup), and pogo pins (mainly the thought of it as I never got around to getting a dock that uses them).