I've been to Riva for a short holiday and just looked for some things I left at home. I found everything, because although this store is very cozy, cute and small they have a huge variety of things. Perfect if you're looking for a snack or some ingredients you just can't find in a normal supermarket. The shop assistant was very helpful.
The shop is located in a small street but not really off the city, so it's easy to go there before going to a cafe or whatever you might do in the town.
Cons: no fresh items