Blender is a free, open source serious 3D modelling tool. At present it is more of an artistic tool; it lacks architectural and engineering design abilities, however there has been a lot of community interest in this area.
From an artistic modelling perspective there are few features which keep this tool short of the competition (both commercial & free). In other areas, Blender excels with its abilities (e.g., fluid and cloth simulation). 3rd party scripts provide abilities not available in the base application, and the list of 3rd party rendering engines is growing all the time (although Blender's internal rendering engine should not be ignored either).
Blender's game engine is making great headway with a useful physics engine, and many fine gaming examples being produced all the time.
Blender will never be "finished", it will just keep getting better.
