I am a mac and cheese FIEND and I've gotta say that I'm disappointed with the lack of vegan mac-serving restaurants in NYC. There's a couple places but the mac is either uncreative (Follow Your Heart dumped on plain noodles) or just plain not flavorful. S'Mac takes the time to make their own vegan cheese sauce (possibly cashew-based), and there toppings go way beyond the usual broccoli offered in most restaurants.
I went with the small mac, which was about $5 and a good large snack (or VERY small meal). I got the usual broccoli, which I just love in mac and I also went with figs just because it seemed interesting. The figs themselves were good but I didn't like them in the mac because the cheese sauce is already a little sweet and the figs made it too sweet for my liking.
Either way, I'll be back for sure to order larger portions with more toppings.
Note that this place is pretty small so it can be tough to get a table. Also, since all the mac is made fresh, you may have to wait 15-20 minutes for your meal, but it's worth it. :)