In terms of calories burned, the elliptical trainer offers an efffective cardiovascular workout. According to figures from Harvard Health Publications, you can burn up to 800 calories per hour working out on an elliptical trainer, depending on your body weight. However, not every elliptical trainer fits every body -- and that's just the first of several considerations you should take into account when choosing a piece of cardio equipment.
It's a Full-Body Workout
Most elliptical trainers come with moving handlebars slaved to the pedals' movement and resistance; pushing and pulling on these handlebars activates the major muscle groups of your upper body, creating a true full-body cardiovascular workout. More muscles worked equals more calories burned. However, just resting your hands on the handlebars without actually pushing and pulling doesn't do much for you -- so make sure you're actually working those arms, instead of just "phoning it in."
One Size Doesn't Fit All
Many elliptical trainers in the gym have a variable stride length, enabling them to fit a number of different body types. But if your stride is very short or very long, you might have trouble finding an elliptical trainer that suits your natural stride -- especially if you're shopping for a home-use elliptical trainer. If the elliptical trainer isn't comfortable when you first use it, it'll never be truly comfortable to use -- and in that case, you might be better off with a bike or a treadmill.