Snapseed's menu of adjustment tools is one of the most impressive I've seen in a mobile app. At first glance, it might look like there are only 13 to choose from, but once you dive in, you'll see that with the submenus, intensity scales (1 to 100), and different adjustment combinations the possibilities are almost endless.
The Automatic tool offers the quickest way to enhance your photos, with its instant color and contrast correction. It works well, and is a great entry-level way of making pics more vibrant before sharing. If you want to get a little more granular with your adjustments, you can fire up the Tune Image, Selective Adjust, and Details tools, which let you adjust attributes like Brightness, Contrast, Saturation, and White Balance. Here you can easily get lost in the number of adjustments and combinations available, so be careful.
And, of course, Snapseed also offers filters. But make no mistake, these aren't the tap-to-apply-style filters that Instagram users might be used to. These filters are divided into categories (Black & White, Vintage, Drama, and Grunge) and each offers an incredible level of control over attributes like noise and texture.
Finally, Snapseed lets you finish off your photos with Crop and Straighten tools, as well as blurring effects like Center Focus and Tilt-Shift. These focus tools can be difficult to use, so be prepared to sit with them for a while before getting your pictures to look exactly how you want.
One thing that Snapseed is missing is a zoom function. As it is now, the editor, always set at full-frame view, makes it difficult to see the finer adjustments that are made. When dealing with attributes like noise and texture, it would help tremendously to be able to zoom in and get a closer look.
Because of the incredible level of control it offers, Snapseed is the best Android app that I've seen for enhancing photos. It comes with an impressive menu of tools, and you can make very fine adjustments that just aren't possible with other apps. What's more, the swipe-to-adjust control scheme makes it a snap (and a pleasure) to fiddle around with photographic attributes. That said, if you're looking for an app to add zany or artsy effects to your photos with, Snapseed probably isn't it. This app is tailored more to people who are trying to add a certain level of polish and professional quality to their work.