This Naturalia location is well-maintained and convenient, located in the 16th arrondissement, just a short walk from the Argentine metro station (line 1). Relative to some of the nearby full-size supermarkets, this store is a bit smaller, probably closer in floorspace to a Monop' or a Carrefour City. However, they've got a pretty complete selection of items, both fresh and packaged, and seem to have made very efficient and productive use of the space they have.
Naturalia is well known for being organic and having a lot of vegetarian/vegan options. If you're looking for things like faux gras or vegan mayonnaise, Naturalia is definitely a good place to find them, as they are either nonexistent or hard to find at regular French grocery stores. They also have some more exotic items that I didn't previously realize might be hard to find in France in the winter. For instance, my local Carrefour and Monoprix didn't appear to sell dried mangos, while this Naturalia location had a few prepackaged options in addition to selling them loose in their bulk section.
However, for other more common products and staples, I would recommend sticking to the bigger chain supermarkets if you're looking to shop on a budget. The items in my normal grocery shop (e.g. rice, chickpeas, veggies both frozen and fresh, spices, charcuterie, meat) were invariably 2-3x more expensive per kilo at Naturalia than, say, at Carrefour. I still really enjoyed browsing here, as the shopping experience is just nicer and more peaceful than at a big supermarket. I was also impressed by the selection of items they were able to fit into the store. If you've got time to linger, it's fun to look through all their offerings, since they offer some pretty unique/interesting items, even if you're not buying everything you come across.
The staff are friendly and efficient, and the store is clean and pretty easy to navigate. read more