My gym just got one of these things in yesterday so I came back this morning to test it out.
20 minutes and I was gassed!
No impact on the joints, extremely high intensity if you do it correctly. Or, if you're a beginner you can just get on and climb regularly.
This is what I did (not a beginner routine btw):
I will be going back to this piece of equipment as a staple for awhile. I love how easy it is on my knees cause I ran track in college and hoop alot now and my legs are dead alot. Could not recommend highly enough!