The advantages of N scale have been spelled out pretty well in the previous responses. Some disadvantages to think about:
1. Much more limited stock.
2 Very limited number of DCC ready steam locomotives.
3. Depending on the era you are modeling, limited number of available vehicles.
The other disadvantages (such as the need for good track alignment, etc.) can be overcome quite easily.
In spite of the disadvantages, I feel they are more than offset by the fact that you can fit twice as much in the same space.
Just make sure you have a good magnifying glass - you will use it a lot!
I have days when I cuss N scale a lot, but I still love it!