I will try and be concise with my reviews, but that is not my strong suit;) We had a camper van for 10 days, and then a car for 7 on our most recent trip. I will list the reviews by category
Vehicle rentals:
Happy Campers--Excellent! We had the Happy 4x4 which was a VW Transporter. Cost was 3K US dollars for 10 days. We brought our backpacking sleeping pads, bags and pillows which made it more comfy for us. Otherwise everything else they provided was great. They do provide bedding, but we wanted our own instead. When you pick up the van, there is an area that fellow campers can leave things behind and you can take. We opted for the Happiest Bundle, which provided the premium insurance as well.
Blue Car Rental--We have used them a number of times and they are great to work with. We had a Dacia Duster for 7 days and the cost was $1350 US dollars. It was a 6 speed manual. No issue with the car or with Blue. We took the full insurance.
Restaurants:
Braud Bakery--There are several locations between the airport and Reykjavik. I preordered/prepaid and picked up our goodies after we were on the road. We opted for the location that was adjacent to Kronan so we could grocery shop as well with just one stop. Their cinnamon rolls are amazing, and they have several flavors such as licorice with blueberry.
Costco--Yes, brunch after our overnight flight was a Costco hot dog. Not like the ones here, but true Icelandic style being lamb and them with the special sauce and onions.
Fjoruhusid Cafe (Hellnar)--We hiked from Arnastapi to Hellnar, and at the end of that trail is this cafe. We had the fish soup, bread, coffee and hot cocoa and it was very good. The cafe is right next to the trail, so easy to spot.
Gamli Baerinn Kaffihusi (Westfjords, just west of the ferry dock)--This cafe/guesthouse is on a farm. We had tomato soup, toast, coffee and cocoa and it was very good. The soup was the best tomato soup I have had. They also have a small area of hand knit wool items for sale.
Tjoruhusid Restaurant (Isafjordur)--This is a huge seafood buffet place that books months in advance. There are two seating a night, one at 6 and one at 8. Family style seating. Everything is seafood. The fish soup was very good, but we were advised by several locals to not fill up on that as the other pans of fish were so good. The main buffet had around 6 or 7 huge cast iron pans with different fish in each. I tried a little bit of everything but still could not eat it all. Most people had at least seconds, which I have no idea how unless they had hollow legs;) My only negative comment is that if you have a sensitive stomach, the oils can get to you.
Litlibaer Cafe (near Sudavik)--Tiny little cafe up on a hill alongside the fjord. Outside tables. Order at the window and they bring it to you. If you order coffee, they will bring you an entire pot to leave at the table with you. Waffles are their specialty, with home made rhubarb and blueberry jams. They also bring real whipped cream in a dispenser. Once again, there is a small area inside with wool items for sale.
Heydalur Farm--This is a hard place to describe. They have a handful of hotel rooms, a couple cabins and a campground. We camped. They also have a natural hot spring, a man made hot spring, and then a full size pool inside a greenhouse. There is a stable on site, so you can ride horses as well. I knew we would stay at this place when I found out they have a 14 yr old Golden Retriever, so we got our golden fix while missing ours at home;) We had dinner in the restaurant, which they ask you to let them know in the afternoon what it is you want to eat, so they can prepare it and have it ready at the time you want to dine. We opted for starters of smoked arctic char which they made to look like a rose. Sounds odd, but was very good. We both wanted the meat (lamb) soup, so a huge crock of the soup was brought to the table and we self served