Blender is Free and Open Source 3d Computer Graphics software that runs on most of the operating systems and alternative to the very famous Autodesk’s 3ds Max, Maya, Pixar’s RenderMan etc. Blender is lightweight compared to Autodesk solutions, offers completive features like Rigging, Modeling, UV wrapping, Animation, Rendering, Shading and many other features that one would expect from a 3d software.
Most recent version is the Blender 2.49 with lots of improvements, Blender is constantly evolving. Considering the fact that the Blender is community driven, it has had its ups and downs.
Notable downside of Blender:
Blender developed as an in-house project and slowly became popular. Its lack of Documentation is one of the main issues. There have been attempts to improve the documentation and many initiatives like Blender documentation project, the 2006 Blender Summer of Documentation project, and the June 2007 introductory book "Essential Blender", which was published by Blender Foundation. It is good know that the Blender community is doing its best to improve things but proprietary software’s do have the best of training materials and videos.
Blender’s UI has also had issues though it offers a lot of keyboard shortcuts, users have felt that the UI is less intuitive when compared to the proprietary counterparts. Again, there have been attempts to improve the UI look and feel, widget support etc.
However the bottom line is Blender community is very strong and it will take big steps in the coming years.
Some of the best 3d models rendered by Blender – Please see Blender Gallery for more details on artists.
Detailed 3D software comparison:
European CG Network – http://www.tdt3d.be/articles_viewer.php?art_id=99
Computer Society for Digital Artists – http://wiki.cgsociety.org/index.php/Comparison_of_3d_tools