Just went to Pizzeria Da Lupo, completing a trifecta of visits to new Boulder neopolitan pizzerias (the others being Pizzeria Basta and Pizzeria Locale). The verdict: the environment is less "refined" and fancy than the other two, but I think the pizza is probably my favorite of the three, and definitely my wife's favorite.
We went on a Friday evening around 5:30 and discovered that it was happy hour. Happy hour meant $2 PBR in a can, $3 "tricolor" salad (basically mixed greens in a vinaigrette) and, most importantly, $6 margherita pizzas. Odd that they don't mention this happy hour on their website - it's a great deal.
The salad was forgettable and the PBR was, well, PBR. (I opted for an Upslope pale ale instead - at $3, worth the extra dollar for both the flavor and the fact that it's a great local brewery that deserves support.) We also tried the burrata starter, which is a pile of rich, creamy burrata cheese (basically fresh mozz mixed with cream) with bits of pistachio and lemon confit on the side, and bread (pizza dough, I think) to eat it with. Heaven. The richness of the burrata is cut by lemon's bite, and the nuts add textural contrast. I could've eaten the entire plate of it, and there was a lot. (OK, I did eat the entire plate. Apologies to my wife. It was delicious, honey.)
For pizzas, we ordered a happy-hour margherita and one with sausage, rapini and ricotta cheese. The sausage pie came out almost immediately, with the server apologizing that the margherita didn't "meet the chef's standards" so they were going to make us another. (A sign either of the integrity of the chef, or that they forgot to put our order in.) The sausage was in fairly dense rounds, still in the casing - unusual for this style of pizza - but was fatty, flavorful and delicious. The rapini and ricotta were also tasty. But the highlight was the crust, as it should be in a neopolitan pie: nice "leopard spots," deep brown spots on the bottom and on the cornicione (indicating the oven was nice and hot), slightly puffy around the edges, with a crisp bottom and chewy middle. The structure was enough to support the slices, but not hard at all. The margherita's San Marzano tomato sauce was a little watery, causing those slices to lose some structural integrity in the middle, but not catastrophically so. And the cheese was perfectly delicious fresh mozz. (They also offer a buffalo mozzarella margherita, but it's not on the happy hour menu.) All the toppings were well seasoned, something I've had issues with at other places in town - I love the basics of Basta's housemade sausage, but both times I've had it it desperately needed salt.
I'm not an expert on traditional neopolitan pizza; I've never been to Italy. But based on what I've had here in the US, although Da Lupo probably isn't the most traditional, it's the closest to my preferences: airy cornicione, good balance of crisp/chewy crust, and flavorful, well-seasoned toppings. Based on this one visit, I'd put the pizza itself at the top of the heap in Boulder so far, but I think that both Basta and Locale have some pretty extraordinary non-pizza items (the wood-fired salad at Basta and the fruitti di mare salad at Locale come to mind) that probably trump Da Lupo's offerings in the "fine dining" category.
One caveat: something I've noticed about neopolitan pizza places is that the dough is so finicky that it tends to change from visit to visit, sometimes dramatically, so until these places have been around for a while it's tough to say whether they'll manage to keep it consistent. Boulder Organic Pizza is the most notable example of this I've seen; my first visit, the crust was excellent. The next visit, a couple of weeks later, was like a different place - soggy in the center and bready all around, it was almost inedible. I haven't been back yet to see if they've gotten things together.