I have a hard time with NAS. For the last couple of years since coming to YLF I have really wanted to participate, but have never had finances and a good grasp of what I would need for fall in line in time for the sale.
I'm usually right on the cusp of being priced out of many Nordies offerings, so NAS is one of the only times of year where I am able to afford to indulge a little. Fall/winter is my HIGHLY dominant season and our Fall and Winter start earlier than most, so buying makes sense. I also have some huge holes in my wardrobe for the season that have been bugging me for awhile, and I tend not to fluctuate much in weight. All are great reasons for participating, in addition to Angie's reccomendations and the fun aspect.
That said, I do tend to get a little blah if/when NAS doesn't work out for me, mostly for the opportunity lost. Facing your actual budget and wardrobe holes for the next season for the first time doesn't tend to be fun if the budget is strict and the holes are multiple. I feel a little pressure to buy and make snap decisions for fear of items running out or higher prices, which doesn't sit with me, but it is still a great opportunity.
I think this year I will see what the sale holds in terms of deals of some of my must have holes, and if it doesn't work, it doesn't work. I also am going to browse for a inexpensive thrill that doesn't have to be a hole-filler as a birthday gift, since by the time NAS items ship to me it will be relatively close to the right time of year, but only if something strikes me.