As far as I can tell, theres no adware/spyware/malware of any kind. I always check downloads and always re-run checks after installing new software just to be on the safeside.
Hit the forums and search or ask questions or just troll around and see if there are any problems people r experiencing with it. The main reason I use it is that it can break most encrypted DVDs and makes it possible to render the copy in a "region free" format i.e. can play on DVD players of any region.
I have not tried to "backup" a DVD from a different region yet to see if it is possible to extract and backup the DVD copy into a regionless version (I will try to eventually) but if that is possible the potential is awesome.
Think of all the cheap DVD's that are on Ebay from Asia. Just buy, backup and render into regionless and play away.