Yes, it is. Besides Ariel's Grotto Goofy's Kitchen is the only character meal at supper. So if you want the birthday meal for supper it is pretty much your only option unless your son likes princesses.
We love it there, it's the favorite character meal of my group. Goofy dances and plays a little game banging on pots and pans with the kids about every 30minutes.
Is it worth it... that's hard to judge. It's quite loud due to the games, not every kid likes that. If he's more shy I'd go for breakfast at Storyteller's Cafe instead. For me being a character maniac most definitely yes, it is worth the money. Even my friends who are not into characters like it because the food is really good. They recommend the Prime Rib and the Blueberry Cobbler. It is one of the more expensive meals though.
The characters at the meal are Goofy, Pluto and Chip & Dale (those seem to be always there) plus assorted guest stars. We've seen Minnie, Alice, Sleeping Beauty, Jasmine, Mulan, Baloo, Aladdin and Gepetto for example.
My second favorite is a tie between Storytellers and Lilo & Stitch breakfast. Lilo & Stitch is now Mickey's Surf Up breakfast, so I can't really comment on this anymore as I went before the change. Storytellers is probably as laid back as Goofy is not.
For table service restaurant our favorite is Cafe Orleans if you're not looking for anything too fancy. Carnation Cafe is also quite popular on here.
My favorite for counter service is Taste Pilots Grill. I loved the Blue Yonder Burger, and my friend can't get enough of the fries. The portion of fries is so big, it easily serves two.