The dining plan is a good value at SW and covers the majority of their foods (not things from snack stands, but most everything else from quick service locations). They do a nice job of marking which items qualify as the meal and side/dessert on their menus. Check out the "SW Dining" sticky, there are lots of up-to-date photos of the menus and you can see right on them what options are included in the dining plan.
You get breakfast, but it's quite limited and not impressive, and can take a while as most everyone getting breakfast is redeeming their meal vouchers so it gums up the line a bit. There are enough interesting actual meal options that I prefer to wait for early lunch & activate then. You can normally get lunch & dinner plus an extra meal or two as a "snack," depending on how long the park is open on your chosen day.
Lines for food can get long at times. You can even grab food and take it to watch a show. The dining plan does not cover food booths for special events such as the Seven Seas food festival or their Christmas food booths.
