(I'm quoting here)
---Graphics Design---
Layers
Near unlimited history (limited by disk space)
Various Brushes
Many special effects and adjustments
---Photography---
Auto-Levels and manual Levels adjustments
High quality bicubic and super sampling image resizing
Magic Wand selection tool
Clone Stamp tool
Red Eye Removal
Ability to acquire pictures from a scanner or camera directly into Paint.NET (Windows XP/2003 only)
---Web Design---
Up to 3200% zoom, or as low as 1%. Grid mode is available for 400% and larger zoom modes.
Control over JPEG quality along with preview of resultant file size
PNG transparency support
---Developer---
Extensively optimized for multiple threads: systems with multiple CPU's or cores will exhibit dramatic performance gains
Full source code provided
Extensible effect plugin system
Try it out guys, I tried it and its a whole new powerful Paint, I hope you give it a chance just like I did.
Enjoy!
Link: http://www.eecs.wsu.edu/paint.net/

