TexturePacker vs Unity Sprite Packer

What is the pros and cons about using TexturePacker or similar sprite sheet packers vs Unity Sprite Packer?

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I’m a huge Texture Packer fan. I can set up my own sheets, it will do HD/SD automatically. In combination with the free ‘Texture Packer to Sprite’ it is truly awesome. I just finished a set of sprites for the Asset Store, and tried to use the autoslice feature in Unity. For simpler sprites it works pretty good, but in my case, there were some ood and broken up sprites that would have required manually tweaking the autoslice results. This free set of tools"
http://forum.unity3d.com/threads/217408-TexturePacker-to-Sprite worked great.

I can control all aspects of my sheets, and make small paint touchups directly on them if required.