Not used either, but ProgeCAD (http://www.progesoft.com/en/products/progecad-smart/) and DraftSight (http://www.3ds.com/products/draftsight/free-cad-software/) have good reviews.
I'd suggest checking out this list - http://blog.cometdocs.com/10-great-free-alternatives-to-autocad and seeing which best fits your needs
Check out ProgeCAD new free version or old free version
Also check out TrueCAD which is not free but not as expensive as AutoCAD and has similar features