That is a pretty crappy review. RegSeeker is not good at all, it can very easily cripple our system. In my opinion (I have used many reg cleaners), I use Registry Mechanic and CCleaner. CCleaner only finds the basic invalid entries and Registry Mechanic will do the deep clean. There is not 1 registry cleaner that will find every invalid entry on your system. It's just that them two programs are the safest for me to use.
Plus, sometimes Windows will just rewrite the delete the entry anyways.