We ate at Dream in Rovinj twice
http://www.dream.hr/hrana_pice_jelovnik_en.html I don't remember what I had to eat but the dessert was wonderful! We also ate at the Camellia restaurant in Opatija, the food was very nice although the service was a bit slow. There was a piano player in the main dining area, we were sitted outside on the terrace.

We are getting married in Opatija end of September and are holding our reception at restaurant Le Mandrac, where the standard of food/service is top notch. However, life is not all fine dining for most of us. While we were exploring the town we found a few little places serving simpler fare, Skalinada up behind the church, Yacht Club in the harbor and a good pizza house, Madonnina, near the Tourist Office.

Stay away from Veli Joze. My husband and I spent a week in Rovinj enjoying incredible food. On our last night we dined at Veli Joze and were both sickened with food poisoning. We should have trusted our "spidey" senses and walked out after seeing how dirty and run down the place was. On a positive note, we had fantastic meals at "Krcma Ulika" (near the hotel Angelo D'Oro), "Scuba" - looks a tad touristy but the hot baked bread and tagliatelle with tartufi was worth two visits, "Giannino" (reasonably priced, good food) and "Da Sergio" for pizza. Also had terrific lunches at "Dream" and "Bastia" in Grozjnan.