I use Inventor frequently (very heavy modelling in 3DStudio/3DMax 10 years ago, with a short stint in Solid Works) and KiCAD is pretty good compared to other stuff for ECAD that's available for free.
Sure it's missing a lot of luxury but has a lot of useful stuff under the hood (*) you wont notice at first and if you're determined enough you can definitely design more exact than the fab can ever hope of achieving.
Get used to the relative coordinate readout right next to the absolute one. Can be reset at current mouse pointer with [Space].
Unfortunately the relative coords are not being used in any masks/GUIs, but you can use 'exact input' for some movements/modificators.
The grid is good to work with and PCBnew with its OpenGL canvas (EESchema is 'older' by that standard and waiting for it's refurbishment) is coming along nicely in the nightly test builds some of use use for production.
PS: file format is human readable and a lot of 3rd party tools/scripts are around that help with this or that.
If you search for @Shack you'll find he's creating scripted 3D models inclusive footprints.. then there are symbol scripts aso.
PPS: The worst actually is getting used to the zoom of the mousewheel. I have Inventor the other way around.. upper wheel forward KiCAD = zooms in, Inventor = zooms out
*) check out the array function for patterns for footprints.