Yes, it is good, but it has to be done in regard with a "normal" UCS, because it uses the bounding boxof the object.
Here you can find how to read the ACIS code of an object.
But I'm sure you'll prefer your lisp
If you are on 2007, be aware that Length, width and height are values that can be read even more easily, in the properties or through a simple lisp
For R2000+ only - 2 more ways:
1. WBlock the box out as an xml file then read the xml file (which is ASCII
text), looking for the 8 lines labelled "point $-1 <x><y><z>" between the
opening and closing headers.
Isn't that last solution brilliant ? (but only works in old version, I think)