I much prefer NS4 for it's restrictions, for example, you can't wear godly weapons, armour and accessories from your first level, which i think is great. Not many modules out there have these kinds of restrictions and it would be nice if more did. i don't miss NS3 too much as some of the areas are farmiliar in looks, like the goblins cave entrance close to the Last Alliance. and the path leading to the deserted villiage also very simular but i think it's great that they are so simular it makes me feel more comfortable with the surroundings having these light simularities.
The only thing i miss on NS3 are the friends i made while playing there, although i can't remember their names i do remember them.