Im not sure about the AKL's Tonga Toast, but at the Kona Cafe at the Poly, its wonderful. Its a thick slice of sourdough bread, cut in the middle and stuffed with bananas. Its made like French Toast then covered in cinnamon & sugar. You get your choice of bacon or sausage with it too. Its very sweet & very filling...and very yummy.
Tonga Toast is one b'fast item that we have to get on every trip. It is so good. My wife & myself always split it because of how big it is. Kona Cafe is one of our favorite places to have b'fast at WDW.
I must be in the minority on this one. I tried Tonga Toast at AKL for breakfast one morning and while it was *okay*, I found it so sweet that after two bites I had enough because I felt myself getting sick. I was sort of disappointed because I had heard so many great things about it and I couldn't enjoy it myself! LOL