The Effects menu houses all of Pixlr's photo filters, which number more than a hundred in all and cover a range of looks, from muted vintage tones to vibrant colors. There's also a Creative effects menu that offers different ways to slice and multiply photos to achieve that Andy Warhol look if you like. You can even adjust the opacity of any filter by moving its Fade slider. This is yet another control that sets Pixlr apart from many other mobile photo editors.
While filters add different combinations of color and light settings to your photos, Overlays provide layers of shape or image-based visual effects. For example, you can add flames, smoke, or circular vignettes. There are also a variety of Bokeh effects that can give different looks to the unfocused points of light in your photos. For any of these, you can change the Fade settings, and even rotate or reposition (vertically or horizontally) an overlay in order to get just the perfect look.
Lastly, Pixlr offers a huge selection of borders in a variety of shapes and sizes. You can choose from different film borders, squared borders, rounded borders, patterns, ripped paper looks, and more. And all of these offer the same Fade and repositioning settings that Overlays do.
One thing to be careful of when editing with Pixlr Express is your device's Back button. Disappointingly, the app doesn't warn you before exiting the editing screen, so you could very well lose your work with one accidental tap. Then, you would have to either take a new photo or sift through your Gallery again to find the one you were editing. For these scenarios, I'd love to see a Recent Files menu available upon launch. Also, it's worth noting that not all of the Pixlr's effects come pre-installed. Many of them have to be downloaded.
Once you're finished editing, Pixlr Express lets you share your finished product to any of your other installed apps, or save it directly to your device's photo gallery. It even lets you choose what size to output (Small, Medium, or Original). If you want, you can set the app to always output at a default size, but I think it makes more sense not to. After all, different platforms might call for different file sizes.