MovieMaker is one of those programs that works (apart from when it crashes), but I can't for the life of me work out why you need it.
Auto create slide show movies
The premise of MovieMaker is simple, it plugs together all your photos in a single folder to make a movie. Import a folder (either by selecting it from your hard drive or dragging it on to the program window), and the program will automatically do the rest - putting the images together in the order they are shown in the folder.
There are some complicated controls to help manage this if you want to make some changes to the default movie (a splash screen filled with hot-key commands is on hand to help with this). Unfortunately, the complexity of this actively discourages you from experimenting. Indeed, I found it easier to reorder / re-tag images in the original folder rather than trying to edit once in MovieMaker.
MovieMaker does have some handy features before you render the final movie. You can select how many frames you want the video to last, how long individual images will be displayed, and the resolution for before you render the video for play. There are also a host of more technical options allowing that let you select the format of movie you want and the codec it will be rendered in.
The thing is, I am not sure what this program is really for. A folder can be set to show images as a slide show, and the video does not provide enough options to expand on this. MovieMaker sells itself as a way to show holiday pics, easily display security footage, or show a nanny cam, but I see no real use case for any of these unless you REALLY need to share the images with someone, at which point this does offer a small file size.
You have nothing to lose if you want to give the free demo version of MovieMaker a try, but its deeper options are too fiddly and its function too limited to really recommend.