Are you a highly skilled computer user? ...
If you do not have knowledge of the registry, then you would probably be better off leaving it alone, and definitely not placing blind trust in a program to do the job for you.
IMO - there is no reliable way for a third party program to know whether any particular key is invalid, redundant or neither. Some registry cleaners may not know for sure whether a key is still being used by Windows or what detrimental effects removing it may have. This has led to examples of registry cleaners causing loss of functionality and/or system instability.