I took Pilates classes from a friend and I thought it was wonderful. It's not strenuous like some other forms of exercise, but I will say that it was more challenging than I expected it to be. When you watch someone doing it, it looks easy like they're just stretching, but when you actually do it, you'll learn that it has to do a lot with breathing and it's important that your form is correct to have the maximum benefits. What's neat about it is that in a sense it strengthens you from the inside out.
I've since stopped taking the classes (partly because of the expense and also because my friend had to temporarily stop teaching for personal reasons), but now that I know the proper techniques, I can watch Pilates videos and know that I'm doing the exercises properly.
I think you'll enjoy it! Let us know how it goes!