Convert Doc is a software tool which main aim is allowing you to convert documents among several formats like DOC, DOCX, RTF, PDF, HTML and plain text. However, Convert Doc also allows you to perform additional actions with your documents like concatenating them, removing their empty lines and searching/replacing specific strings within them. Also, you can save your conversion jobs for later execution.
In my opinion, the program's user interface is a bit hard to understand and use, which makes it little suitable for novice users. Basically, it's divided into four panels, one for selecting the action to be done, another one for selecting the source files and conversion method, another one for selecting the output format, location and advanced options, and the last one for listing the pending conversion jobs. As for the action to be done, you can select between simple file conversion or special processing, which allows you to execute one of the actions mentioned above, like file concatenation or string replacement. The input files can be selected either individually or by folder, which would be the right option if you want to convert multiple documents at once.
The program offers you three conversion methods - "Convert Doc" (which doesn't require having MS Word or Adobe Acrobat installed), using MS Word, and converting from PDF to any of the other supported formats (specific for PDF source files). According to your selected output format and conversion method, you can configure all the detailed parameters such as page ranges, output quality, PDF settings and others. Once you finish configuring your conversion job, you can start it immediately, or add it to the job list for later or batch execution.
As I mentioned above, Convert Doc supports converting all the documents contained in a folder at once, however, if you require converting lots of documents spread in multiple folders, it's very advisable that you use the program in command-line mode. It is specifically designed for batch conversion of large amounts of documents, and supports plenty of options you can use to define all the conversion parameters according to your needs.
In a nutshell, if you are willing to get familiar with the program's interface and command-line usage, it may be very useful to you, especially if you need to convert lots of documents quickly. However, I would say the program's cost is a setback for it. Undoubtedly, this is one of the most expensive tools of its kind.