Just went to my 3rd class today, and getting hooked already. My local gym tries to help that addiction by offering the first month at $29, and then it goes up to $100.
So, anyway.... I'm feeling a little weird in my knees and my neck is a little sore, but other than that, I love the energy from it. Just need to drink more.
But to go 4-6 times weekly? That's a lot of extra time, on top of 6-10 hours of running. Hmm. For the moment it has completely replaced any strength training that I was doing (which was light, anyway).