I've been a Copernic Desktop Search user for a few months now and am still somewhat amazed and saddened that such a great product can go relatively unnoticed thanks to the popularity of companies offering products that barely bother trying to excel in the field (ahem, Google). I initially tried Copernic after reading a CNET review which is now outdated thanks to newer versions of the Google Desktop Search and MSN's new offering (which is MUCH better than Google's but not good enough to make me consider replacing Copernic).
Yesterday, Search Engine Watch pointed to a review that agrees with my assessment.
I do find it strange that the author listed a lack of Outlook indexing as a "worst feature" of Copernic because the feature isn't missing at all and is probably my second favorite feature. Being able to search emails (and attachments) and see the results in the preview window with the search term(s) highlighted (opening Outlook is optional) is great and was how I was able to uninstall LookOut.