Hi, Susanne!
Memory Maker can be purchased prior to your vacation, allowing you to view your photos online through My Disney Experience. Purchasing it ahead of time also allows you to get the service at a discounted rate.
You can also purchase Memory Maker at full price at the parks in most gift shops. If you go this route, you will need to link your Memory Maker to your My Disney Experience account before you can view your photos online. You would also need to link any PhotoPass cards or any photos from your MagicBand of previously taken photos.
In my experience, if we have Memory Maker, we make sure to use it! On our last vacation, we took so many great family shots that we would not have otherwise had. (It seems I am always the one taking pictures of my husband and kids...it is nice to be included in the picture with the great Disney photographers taking the pictures!) My kids especially love the ride photos and the even the videos from Seven Dwarfs Mine Train and Tower of Terror.
I also like the quick access to the photos and the ability to post the pictures to social media. It is so quick and easy!
You can read more about
Memory Maker before making your decision, but I really think you will enjoy the convenience and FUN of having it. It is a great way to preserve all of your "Unforgettable Happens Here" moments!
Wishing you a magical vacation!
Cathy