Without question, the best Italian in Long Beach/OC area is Christie's on Broadway at Termino in the Belmont Heights section (in between Belmont Shore and downtown). Excellent pastas, steak, seafood, poultry--you name it. My favorite is the chicken fiorentina (chicken breast stuffed with spinach and fontina cheese and a reduction sauce)....reasonable prices, food is delicious and an outstanding and extensive wine list. I think the number is 562-433-7133; reseravtions a must on weekends. Owner Christie Bono is the daughter of the late Sonny Bono and she also has a second restaurant in the Naples section of Long Beach called Nico's (named after her little boy) that is also excellent.
Another real good Italian restaurant is in Belmont Shores on LaVerne, just 20 feet south of 2nd Street, called Cafe Gazelle. Very small bistro like restaurant, but excellent spices and dishes including veal and pasta (especially if you like garlic). Small but excellent wine list and you cannot beat the prices--typical entree with ceasar salad and fresh baked bread is less than $ 14.
Finally, in downtown Long Beach there is a great little restaurant called Mama Tina's....it is located a block west of Pine Avenue, near the Blue Line. Good, home-style Italian the way mama used to make it.
I am not a fan of L'Opera (place to be seen--food is not better than a franchised Italian restaurant you can find in Orange County)...Andiamo is not bad...try the 3 I mentioned above--you will not be disappointed.
Ferraro's in Long Beach, at Palo Verde and Los Coyotes diagonal is like home cooking. They recently opened an Italian bakery in the same strip mall; haven't tried the bakery but have heard good things. Have only had pastas at Ferraro's but they are good - New York style Italian food. Casual place, reasonably priced.
Ecco's pizza on Bellflower in the Los Altos area of LB, and their new take out place on PCH in Seal Beach (at Zoeter school, where the Wherehouse is) has a good pizza.
L'Opera on Pine for the more gourmet Italian meal. They own/run a number of places. Pretty place, and I remember good veal dishes.
People swear by Andiamo's in the Marketplace, but I remain unimpressed.
If you go a little farther south into Huntington Beach, try Mangia Mangia on Goldenwest at Edinger (in the Home Expo center). Consistently good, reasonably priced, good service.