Night flying's fantastic. Although I agree with the above that engine failure in a single is a somewhat scarier prospect at night - I guess I'd tend to err on the side of stretches of water, where available.
Apart from that though, definitely go for it. At the very least it gives you options at the quieter ends of the day around sun up and sunset when there are few others around, and you get some beautiful skies. It extends your hours quite considerably, which is a big plus for cross countries and the like. And the air can be wonderfully still at night - it's more like flying a sim at times.
And there's something great about runway lights at night, eh?