Except when searching by metadata doesn't find what you want. Or when it finds too much. This is now 99% case for me when I use spotlight.
I have a huge library of PDF books (tens of gigabytes). If I search for a bunch of keywords or even if I know entire title, the damn spotlight returns way too many irrelevant results. Now I could perhaps spend 10 - 20 seconds thinking about how to write a more specific query, but it's faster to actually go to ~/Reference/Computer Science/CS Theory/ and get right to my damn book, which I know will be there based on how I structured my filesystem and the topic the book covers.
This has in fact gotten worse since snow leopard, before the default was to show file name matches first then content matches. So if you want a book on algorithms, almost all CS theory books will match. You have to type filename:"book title" to be more specific.
Now one could argue that Spotlight should get better. But I'm arguing that you will always encounter cases where it will be really difficult to find what you want, even if you know a lot about what you are searching, let alone if you vaguely remember a detail about what you want to find. But by being able to restrict what you are looking for you will have better luck.
Searching for photos is much easier, because photos are binary content, so apart from EXIF there is not much to look for in there. But if you have documents with plain text or searchable content like PDFs, things get a lot worse.
I agree that Spotlight is dreadful. But that's not really an issue with metadata per se. After all, OSX is still primarily a traditional directory-based OS.
> it's faster to actually go to ~/Reference/Computer Science/CS Theory/
That's fine if this is the only way you ever want to structure your documents, and if you've not got too many of a particular subject. Say you've got hundreds of CS books, some of them have stuff about graphics in them, some of them have stuff about OSX programming in them, and some have both. Now you want to find a book about OSX graphics. Did you store them by subject (maybe not, because the books have loads of topics), or by OS (most of them are OS-agnostic, and some cover multiple OSs, so again maybe not). Do you remember where you stored it?
This is a pretty simple example, but it's exactly the challenge I face on a regular basis when using the fixed hierarchy of the filesystem. Do I store info about my motorbike crash along with other letters I wrote in 2008, or with other info about my bike, or other info about insurance, or medical issues etc? What I want to do is tag it with all of those things, because I might be looking for it for any one of those reasons.
If you want a hierarchical approach, then Lightroom as an example shows how you can still do this - it just allows you almost total freedom with how you do it - files can be in as many collections (and as nested) as you want.
I have a huge library of PDF books (tens of gigabytes). If I search for a bunch of keywords or even if I know entire title, the damn spotlight returns way too many irrelevant results. Now I could perhaps spend 10 - 20 seconds thinking about how to write a more specific query, but it's faster to actually go to ~/Reference/Computer Science/CS Theory/ and get right to my damn book, which I know will be there based on how I structured my filesystem and the topic the book covers.
This has in fact gotten worse since snow leopard, before the default was to show file name matches first then content matches. So if you want a book on algorithms, almost all CS theory books will match. You have to type filename:"book title" to be more specific.
Now one could argue that Spotlight should get better. But I'm arguing that you will always encounter cases where it will be really difficult to find what you want, even if you know a lot about what you are searching, let alone if you vaguely remember a detail about what you want to find. But by being able to restrict what you are looking for you will have better luck.
Searching for photos is much easier, because photos are binary content, so apart from EXIF there is not much to look for in there. But if you have documents with plain text or searchable content like PDFs, things get a lot worse.