Copernic has been in the Desktop Search business for a long time. It is decline in two editions: the Lite (free version) and the Full version. With version 4, the free version has lost a few features that I liked for my home use such as: I can no longer search my external hard drive and it is now limited to only 75,000 files. My music collection is no longer searchable :(. Also, the ability to search Microsoft Outlook is no longer available in this free version but I do not use Outlook at home. I can see why they removed that feature which is more business oriented.
As for the interface, both versions have the same with a few minor differences but it does not impact the general use of the product. Version 4 brought a new interface which fits the new flat-design trend which is ok with me. Compared to Windows Search, it is a nice interface to search with the preview pane and the added refine fields.
Compared to X1, we do not really know where Copernic is going. It seems they are keeping their focus on the home user and small offices but it would be nice to see something new from them.
Also, Copernic does the job for me but the price point of 50$ for a desktop search is quite expensive for me. A price point around 20-25$ would fit my budget.