Hi, Stacy,
I think Margaret is great. Low-key, funny, warm personality. Workouts are all endurance-based and very safe and gentle. Great for an off day with light weights or a tough endurance day if you up the weights. She's had a half hour show on PBS for close to 15 years, which is where I discovered her. Her tapes are pricey so I've never bought them since I get the show on TV, but she's a class act so I imagine they're good. I don't think she has any aerobic tapes, but she has made some walking audio tapes that are fun. She may not be for you if you like to have an all-out sweat-fest every time you work out, but I find her a welcome change of pace from time to time.
--Ann