I started jumping rope a few weeks ago, and I could barely do 5 jumps without stepping on the rope accidentally.
Slowly I started getting better, til now I can do 20-30 jumps without a trip-up.
It is a HUGE heart/lung exercise. Really gets your heart pounding!

I really enjoy it! I can do it in my basement on a rug, and the rope just clears the ceiling.
Sadly, I think my right knee is objecting to the jumping for now, it seems a ligament on the side of my knee got pulled or strained. It's hurting, and I need to let it heal before I take up the jump roping again v-e-r-y slowly and carefully.
I've even had to stop my fitness walking until it heals some more.

If my knee starts behaving better, I have high hopes for jump roping as a bone density building exercise.