Having tried it, here is my take on cross fit:
Cross fit is great if you want to get good at exercise. But it's not specific. It's not going to make you a better runner, or a better, cyclist, or a better waterskier. As a form of exercise, it's great but cross fit isn't specific enough to make you better at any one thing. Heck, even the athletes competing at the highest levels of cross fit competitions don't train by doing cross fit. They train by doing specific training.
If you want to win at your sport (whatever that is), cross fit isn't going to make that happen. Specificity is going to make that happen.
But if you want a form of exercise to get you off the couch that is not only brutally hard but also a ton of fun, then cross fit fits the bill perfectly!