I CrossFit 5 days a week (about 5-8 WODs - workout of the day - each week).
My involvement has changed my life... I'm a better mom, a better wife, a better friend, I have a better relationship with my faith... and I really attribute all this positive change in my life to starting CrossFit.
I've lost 115lbs over the last two years.
It is absolutely scalable to YOUR fitness level. When you go into the box, a coach will send you through an assessment workout to determine where you are in your abilities. From there, unless you have previous olympic lifting experience, they will send you though a multi-week on-ramp program with other new people with a skilled coach. They will teach form, lifts, jargon, and just about anything else you need to know to get out onto the main floor. You'll feel comfortable at that point.
So don't worry about not being able to do everything that others are doing... it's not about them. It's about you. And you'll never find a more supportive team environment. No one sits there and looks down on anyone! It's all about uplifting one another and taking pride in the accomplishments we all reach on our own time.
CrossFit has absolutely changed my body and my mind. I love it!