General Features:
Create paintings with dimensions up to 2048x2048, Full support for all Retina devices, Background autosave, Unlimited undo and redo, Simple and approachable interface
Full screen painting, Record and replay paintings, Ultrafast OpenGL-based painting engine, Huge brush sizes up to 512x512 pixels, Simulated pressure, 64-bit painting on the latest hardware, 14 parameterized brush shapes, Adjustable brush settings (spacing, jitter, scatter, etc.), Adjustable color opacity, Invert color and desaturate,  Flip and arbitrarily transform layers, Adjustable color balance (iPad only),  Adjustable hue, saturation and brightness (iPad only)
Create up to 10 layers, Lock and hide layers, Lock layer transparency, Adjust layer opacity, Duplicate, rearrange, and merge layers, Change blending modes: normal, multiply, screen, exclude
Import and Export:
Integrated with Dropbox,  Import native Brushes 3 files, JPEG, and PNG files,  Export as native Brushes 3 files, JPEG, PNG, and Photoshop files (with layers), Place images from your photo album into paintings, Copy paintings to the pasteboard, Tweet paintings, Post paintings to Facebook
Zoom with two finger pinch, Zoom in with two finger double tap,  Zoom to fit with two finger double tap, Toggle interface visibility with a single tap (this can be changed to a two finger tap in the app settings), Tap and hold to access eyedropper tool