Free one is fine for basic checking of modules and clearing individual codes as long as it's not some of the newer vag models. Post 2004 ish, they used can-bus which the free item wont read.
The free one is fine on my 1995 golf and ok for 85% of the modules on my 2003 RS6, but it won't read my 2005 vw touran.
I have now purchased a proper one from Ross-tech.