This is near the zenith of one of the world's great wine bars, and I have been here maybe 10 times…read moreover the years. Something unique about Paris is the wonderful specificity of little shops, like a place that just sells handmade umbrellas, or food from Puglia, or a traiteur with delicacies from the Auvergne. Willi's is like this for wines of the Northern Rhone valley, where Syrah reigns as king. If you're particularly passionate about the savory and complex wines of this region, this is one of the best places on the planet to find these wines, many allocated or 'culty', for prices on the list that are sometimes even less than US retail. The list isn't just restricted to this region, while Cornas, Côte-Rotie, St. Joseph, Crozes-Hermitage, Hermitage, and others are extremely well represented, you'll also find some terrific selections in areas like the Langedoc, Bandol, and Provence in general.
The food has been consistently good for me, and while it's not breaking any boundaries, I have enjoyed over the years a simple roast chicken with purée, a l'onglet de boeuf Charolais, duck, a sharp arugula salad, and desserts like a baked apple compote and a rich chocolate cake with crème anglaise. I have no idea what Lynette Z. means by "cafeteria style" in her review, but I'd like to eat and drink at this cafeteria.
Yes, there's swag to purchase, and I love it. From the punny Sac à vingt (i.e. vin) chiens, honoring the original dog Willi, to postcards picturing the wine-themed posters that a different artist designs each year for Willi's, to the posters themselves, Willi's also sells a few bottles you can take away. Mark Williamson is often on hand and it has been pleasure to chat with him.
Highly recommended, for years now.