Hi I went to Hermosillo, last summer. HOT over 100°F, The beaches are nice, Go visit San Carlos, nice place, hills, nice hotels, but if you want peace, Go Visit Kino Bay, is a small village, with a beautifull Beach. Be careful when you drive in Hermosillo, Theres no Highways, Freeways.. You have to drive in the city all the time, people are not really carefull driving there, so.. watch out when you cross a traffic light, (I mean.. see cars and people walking..) About the Food.. you have to try the Tacos.. you dont have idea.. Have you ever tried the ones at Taco Belll!! Awfullll... go there and try real real real Tacos.. I recommend a place called "Taco Hass" and ask for "Caramelos" this is a taco made of grilled beef with morzarella cheese served in a white tortilla (with a taste indescriptible, nothing compared with the ones in USA)... and you can add if you like.. Avocado, Salsa, Lemon...
They actually have a bar with a bunch of stuff you can try with your Taco. Other nice Restaurants are located at Blvd. Rodriguez... I assure you.. you wont starve in Hermosillo, because they have several types of food that you can try without getting a "Stomach problem" in Fact they have international restaurants, you can find whatever there. People is kind, very nice people. You have to know spanish.. that's for sure. not everybody speaks English. Another Advice.. Never.. Never drink water from the sink.. the water in Hermosillo came from under the earth.. and it's not really good tasty. Buy purified water such as "Alpina Glacial, Electropura" Visit the Zoo, it's a nice place.. if you like the desert.. they have cactuses and all those nice plants from the desert..
even the animals (OF course.. Hermosillo is near the desert) if you come from a cold weather place.. then wear cool.. you wont like to melt in that heat.. in Winter the weather is over the 60°F higher and lower it's about 40°F but it's barely cold in there.. so dont worry.
Hermosillo is a peaceful city, you wont get robbed.. you can walk at night and nothing bad would happen to you.. at least in the big streets where other people are walking too. I never went to the poor neighborhoods...so I cant tell In most of the places, they accept credit and debit cards.. but some other places dont. so You have to carry money.. dont worry.. they accept Dollars everywhere, you dont have to exchange currencies. Theres so many things to talk about Hermosillo, but you have to see if by yourself. So if you're planning a trip right away.. Enjoy it. Have Fun

Write if you want another advice, I'll love to help

Brian