Wow what an unbelievable, almost foreboding mountain. You almost wouldn't know you were in New England.
I took the Hunt Trail up then Knife Edge to Pamola, and back. Can't comment on other trails but Pamola was great and definitely has its own sketchy parts. The Knife Edge is not as scary as people make it out to be but it's very rocky so you do want to be really careful and not twist an ankle. There is also a very large plateau on the way to Baxter Peak that's very unique in its own way.
I will definitely return to Katahdin to tackle it from the Roaring Brook (east) side so I can take Cathedral up, but wow. What an unbelievable sight.
Really the only downside (which I know is intended to keep the trails from being overrun and becoming dangerous) is how hard it is to get parking. If you are from out of state like I am, have fun. My best advice is to have a friend who lives in Maine.