I have been riding a nexus 7 for over a year. Here are the points I think have not yet been discussed:

The wheel is a pain to get off. I dread doing it. But not because of the hub or cable routing, that is a snap. I dread taking the wheel off because the lock nuts strip like crazy due to the notched thread on the axle and the fact that you have to get them on VERY tight to avoid slipping (in horizontal dropouts). I can usually only get three or four wheel removals out of one lock nut. I have purchased several spare lock nuts to solve this problem. Before you say it, this is not because I am an incompetent mechanic, it is well documented problem and the great Sheldon Brown had this problem as well. His solution was to grease the axle, which does help, but at the end of the day it is still difficult and nothing like a quick release hub.

Also, you need to get a J-tek shifter for any Shimano hubs. The stock shimano shifters suck as they are marketed to the casual rider, and not built for serious use. Once you solve this problem, the internal hub with a J-tek shifter is about as high quality shifting as can be had. It is like shifting a winchester rifle.

At the end of the day I use the internal hub because I like it better. I think it is a better solution for a commuter bike. 7 gears are plenty. I live in Denver where I regularly have huge ascents and descents on my rides. I could certainly use more gears, but you loose a lot of health benefit to riding if your constantly flattening out the hills with a wide range of gears. The fewer gears force me to push hard on the steeps (build muscle) and keep to reasonable speeds on the downhills so I dont die (30mph top speed). Granted, I could get better times with a full range of gears, but thats why I said its a good setup for a commuter, not a race bike.