I think having the option of both is great. I am more motivated when I go to the gym but last night my husband pulled out the dance dance revolution game and me and him went to town on it. The game said that we burned 3000+ cals on it. We weren't doing it for the workout but we kept competing for hours and today we woke up sore. He lost 4 lbs and I lost 1 lbs but we had so much fun and we sweated a lot. I might start using it more when I don't feel like going to the gym. I could barely walk up the stairs.
I would say get a gym membership just incase you feel like going to the gym but i know a lot of people who enjoy working out at home.