Here is a run down on the restaurants in MGM... and my opinions:
Brown Derby... more upscale and a bit pricey. The food is definitely good, though, as is the service. My DD was a bit bored, but the adults really liked it!
Mama Melrose... a nice, laid back Italian restaurant in the atmosphere of a New York Italian eatery. The food is fantastic, the service is good, our only complaint is that the waiting area is a bit small, and they could use a lounge with a full service bar (since they moved the Christmas shop from next door to Sunset Blvd, it would be a perfect spot to annex it to Mama's), since they got rid of Cat Walk Bar off the back of Brown Derby. My DD really loves this restaurant, and it is right across from Muppet Vision 3-d.
50's Prime Time Cafe... our favorite restaurant onsite. The food is homecooked and wonderful. The service is quick, but not hurried. The desserts are "to die for", and you better make sure to keep those elbows off the table, the feet off the furniture, and for goodness sakes, eat those vegetables. This place is SO much fun... we never miss a chance to go! They have a nice lounge with TV's playing old 50's TV shows where you can wait, and it has a full service bar.
Sci Fi... the desserts are good, the theming is pretty interesting, and the kids like the old monster flicks. Food wise, we weren't overly thrilled, though.
Hollywood and Vine.... buffet dinner only... no characters. The food and service are good, but I think they did themselves a disservice by discontinuing the lunch time character meal. It is set up like a vintage 50's diner, with plenty of chrome and formica.
Pizza Planet... basically, counter service pizza. Very loud, as there are tons of video and arcade games there. Pizza is not the best, but the kids seem to like it.
ABC Commissary... not bad... typical counter service, but lots of seating.
