I have an 8 ft trampoline in the garden - it is really low impact on the joints, two sessions a day in the warm weather gives me an increased heartrate, I can do stretching and roll about on the apron in ways I could never think of on a hard floor, and it is fun. I have never had so much as a twinging muscle afterwards, though I have had to admit that my joints are never going to fold like they used to - and it is about 12 years old now and still going strong.
It is also useful if feeling a bit 'bunged up' as the jumping gets things moving really well. Sometimes I am glad we have a downstairs loo.