Nanluoguxiang has gone downhill over the years and is considered as yesterday's story by locals. All the good bars, restaurants and shops have moved away in recent years due to the outrageous increase in rent. Now it is all about shops selling snacks and souvenirs. Nothing that you can't find elsewhere.
Hutongs are everywhere, just take a random walk through any of them.
Having said that, nothing wrong with a first timer with only a day to spare to walk through Nanluoguxiang. I just don't bring my friends there when they are visiting.
Here is an interesting read: http://www.timeoutbeijing.com/featur...n-hutongs.html