I am new to tagspaces, but I was immediately impressed about its ability to visualize and search tags. In fact, I did not yet create any tag myself - I didn’t have to. Because I already had a habit of adding simple indications to my pdf filenames, things like [p] for a paper, [w] for a web article saved as pdf, and also [REM] for a pdf with comments or marks I made on it (to be sure that I would not by accident remove a pdf where I made jottings of kinds).
And, because I happened to put my tags already in square brackets, usually right behind the year (as I use to name pdf books and articles by the Chicago CSE author-year-title convention), I discovered to my great pleasure that tagspaces automatically recognized those bracketed words as tags, even while they were not at the very end of the file name, and magically showed them in its beautiful, colored and very visible way, making the tags spring out, like it was never possible in windows explorer or other file managers. And I could immediately search for documents with these tags in a performant way. To me, this surprise testifies of good software design.
One remark, but it is something that does not bother me much. New tags are automatically added at the end of the filename, right before its extension. There is nothing like a RegEx by which I could say: add new tags right behind the year in the name (something like “\d\d\d\d[tagname]”). However, what I do is add the first new tag via the rename option (F2). It is very nice that once it is there, it remains there even as you add more tags. I did get a few errors, but doing a file list refresh after a rename helps.