I think it helps tremendously, at least if you can get a fairly heavy rope. If you get a speed rope that cuts through the air easily yet is still light, then it doesn't do nearly as much, but just starting out that's probably a good thing. I've heard that due to the impact involved you should not do any more than 15 minutes, but 15 minutes is supposed to be the equivalent of 30 minutes of running. That just really depends on your rope though, there are huge differences. I've went from 172 to about 154 or so over the winter, and jumping rope and giving up soft drinks on a regular basis is 95% of my success.
Personally I use it to break up my normal routine. I don't like to time myself, so I count reps instead. I'll do 200 or sometimes 250 reps of jump rope, then will do pushups, then 200 jump ropes, then curls, then 200 jump ropes then sit-ups... on and on while not stopping while doing other things in between. I'll usually get in about 1,400 of them anymore along with several other exercises. This will take me about half an hour.
But yeah, if you get a decently heavy rope, you can easily make your heart about jump out of your chest. Speaking of which, that's one thing you need to keep an eye on. Your heart rate can spike easily while jumping and it can sneak up on you if you push it. There's been a few times that I literally thought I was going to have a heart attack.