PicMix Lite has promise as a multi-image editor, but due to a hard to navigate interface and a lack of advanced editing tools, it doesn't do quite enough right now to be recommended as a standalone tool. The bare-bones interface, multiple menu levels, and lack of instruction for use of the most important tools in the app, make for a frustrating overall experience in many cases.
One of the first things you will notice when you open PicMix Lite is how bare the screen is. With one button and no images, you start literally from scratch. After loading one image, you can start moving through menus, but rarely does the app provide information about what each option does or how to optimize your results. Most images are downsized by the app as well, reducing resolution for editing. This isn't required, but is always recommended, and if you choose not to resize, it will slow the app down. While there are other editing features, like rotation and cropping, the core function of PicMix is to overlay images on top of each other and then edit the foreground images. You can add more than one foreground image, but the background image cannot be edited. The resulting lack of options for how the two images integrate means the app doesn't do a whole lot other than those simple overlays.
If you want to cut out a person and place them on a background image or play with collages, PicMix Lite will work well for your needs. Because you cannot zoom, however, and because the app offers few other filters, the resulting images will never be quite as attractive as they might be in similar apps with the same cutout technology.