parametric cad

Hi,

Hope someone familiar with Autodesk Inventor and/or parametric CAD
will post some helpful comments/insight on parametric CAD for one who
is only beginning to dip his toes into this "new" stuff.

I am currently quite happy with R14, but had got my itch hands on a
Inventor 5 Hands-on Test Drive/30 days trial version curtesy HP.
Initial tinkering with it has got this old dog a little exited but
apprehensive - reason being one have to start with sketching to be
followed by introducing constrains (angle, tangent, dimension, etc.)
and as one addicted to the old fixed ways, am afraid that one can
easily overlook something leading to small errors (in dimension,
etc.). Is this likely to occur as it appear to me that parametric CAD
needs a higher dimension of geometry intuition. I hope dearly to hear
from someone who also started with something like R14, but is now
happily doing Inventor/parametricCAD OR has turned his back on the
new fangled thing and has gone back to R14, etc.

Thanks

lee