I’ve used mini trampolines for exercise.  I’ve used big ones too.  I’ve used the whole gym that oftentimes has equipment such as trampolines for the gymnasts.  That’s always been a fun way for me, and frankly with all the jumping and if you also combine it with greater flips with the bigger trampolines, it takes some effort and some calories moreover.  Traditional backyard trampolines and bigger trampolines, even in the gym, are quite risky and there are quite a few accidents, mostly due to reckless behavior on the part of users.  It is always good not to do it alone.  However, with the mini trampolines, you can get a certain amount of calorie burning, though not the high flips of course, and you don’t run the same risks.  So they’re not a bad idea in various different ways in general.  You should definitely check out your local store for the mini trampoline, and if combined with other cardio exercises and otherwise exercises that would help you to lose weight, it could enhance your results in general, and therefore you could get greater results in general, which is never a bad thing.  Many have found this complimentary exercise to be just the thing that they actually needed.