Trixter classes....very difficult??

I have just joined a gym and it runs trixter (spinning) classes. I started exercising seriously mid June when I joined MFP. My fitness level has risen quite significantly but I still have quite a bit of weight to lose and I know that I have work to do before I am really fit. I was a bit put off by comments from the trainer who runs the trixter class who said she had a group of men who had been attending the class for a year and were really fit now. I feel that I may not be able to keep up and so haven't attended the class. My thinking is that I should work on really improving my fitness before I even attempt the class. But on the other hand, attending the class might improve my fitness. But it could be painfully embarrassing if i STRUGGLE! Any thoughts, experience or advice appreciated!!