Hi Shyanne,
I've been to the new Be Our Guest restaurant for lunch and dinner. They both have terrific food in a beautiful atmosphere. You can see the
menus for both options on the Disney World website.
At lunch, you'll have good food served quickly. At dinner, you'll have more elaborate food, with more options, brought to you by a server at a more relaxed pace. At dinner you also have the opportunity to purchase beer and wine, which is not available at lunch. I personally slightly prefer the dinner food, but it's really dependent on what you're in the mood for. If you're just interested in seeing the space, then choose the time of your meal based on your schedule and your budget.
I can tell you that "The Master" (aka the Beast) typically only appears at the restaurant at dinner. If seeing him is your main goal, then you should make dinner your priority. If dinner doesn't work out, you should know that the Beast also greets guests sometimes at the France pavilion at Epcot along with his friend Belle. Stop by the Guest Relations office at any of the theme parks and ask them to call the "character hotline" for you. The hotline will be able to tell you exactly where and when any particular character will be appearing at the time of your visit.
Good luck with your planning. Please let us know what else we can do to help.