In poly modeling you will have not the precision of a nurbs modeler in Booleean operation or geometric construction!
A circle is not a circle, a sphere is not a sphere :)

After all depend of what do you want modelise
The more easy modeler (and free) is google sketchup !
Same ergonomy than Moi so a very speedy curve learning!
After one hour you can modelise anything (except human anatomy) :)
http://sketchup.google.com/intl/en/index.html
< Is box-modelling taking a polygon-modeled box and deforming it?
yes Google sketchup can do this :)
http://www.youtube.com/watch?v=bPbb8PPGtVg
Fredo Scale by Fredo6 a crazzy French guy : a must of plugin! ;)


If you want make some organic thing try Sculptris (free)
Perfect for human anatomy
http://www.sculptris.com/

Have fun modeling! :)