Prior to the update, Apple Photos users would have to open an image separately in Pixelmator Pro, make edits and then sync everything back to their main library. Now, any edits made using the extension can be saved directly to Photos. Any layers or nondestructive edits will be automatically saved in an associated Pixelmator Pro document. Using iCloud, files saved to the Apple Photo library will sync across multiple devices. This will be a massive timesaver if you're the type who likes to switch between editing on your iPad and your desktop, or your work and home computer.
Hummingbird comes with a new Zoom tool, which has a more responsive navigator. An updated Crop tool has a Delete mode and the ability to crop to custom pixel sizes. Also new is the ability to drag and drop layered files directly into existing images, refresh Slice and Paint tool presets and better performance for documents with a large number of layers. Hummingbird also offers templates for all Apple devices -- sure to make life easier if you're designing for Apple Watch or iPad.
Adobe is expected to release the iPad version of Photoshop sometime this year, but until then, Pixelmator Pro is a worthy alternative. Given the more affordable image editor's improvements, some may even choose not to convert. Existing Pixelmator Pro users can upgrade to Hummingbird for free. New customers can download it from the Mac App Store for $39.99. Pixelmator Pro requires macOS High Sierra and a Metal-compatible graphics card.