My husband and I did it last year (he actually proposed to me on day 4, overlooking Macchu Picchu). Do you have any specific questions?
It is an amazing experience. It is not easy, but totally worth it. You go up, up, up, then down, down, down, then up and down again. But while doing so, you see amazing valleys, mountains, etc. It (literally and figuratively) took my breath away. I would definitely train in advance for it, as far as getting in shape. I don't have the best knees, and after 5 or 6 hours of down steps on day 3, I could barely take another step down without cringing. But, then I got up on day 4 and hiked the rest!
It gives you a sense of accomplishment to stand over MP, looking down, feeling like you earned the view (you come in differently than the buses, so you end up seeing a view that a lot of people don't see).
I'll try to figure out how to upload pics...
Edited to add: I added two pics below - the rest aren't on this computer....