It's a markup language with a long history I won't get into. But that means it at least aims at separating content and presentation. Relative to producing a document in something like Word, it has a few real strengths. It's very good at:typesetting mathematical notation, typesetting different languages properly in the same document, and pretty good managing large complicated documents. It tends to do hyphenation breaks and spacing better than word processors.
You can easily solve versioning and collaboration issues because the input is plain text (like source code, just version control it and use patches, PRs, etc.) This works better than "track changes" in practice, especially with multiple authors.
So those are the upsides. Downsides: it's a bit esoteric, and clunky for lots of documentation tasks. The implementation is complex and the package/module system can step all over itself. If you have output that is nearly but not quite right, it can be a real bear to fix it.
These days Markdown may be a better choice for a lot of simple documentation tasks where you don't care much about the final output presentation details. Any word processor can probably let you do some things more quickly.
When I was a grad student I knew multiple people in STEM fields who tried to do their thesis in Word (or equivalent) and gave up in frustration, moving it all to LaTeX. I never knew anyone who successfully went the other direction. I don't know if that is still the case.
If you use it a lot, you may find yourself wanting to use it for everything (letters, resumes, presentations, etc.) but many of those things aren't particularly strengths. If you don't use it a lot you will find it hard to come back to casually.
One other strength I should mention, especially for automated documentation. Knuth was very particular about stability in TeX, and LaTeX has mostly-kinda-sorta followed this philosophy. So unless you have used a lot of marginal packages or something, it's entirely reasonable to expect that processing a 20 year old input will work fine using current builds. This is not something you can say of most systems.
"When I was a grad student I knew multiple people in STEM fields who tried to do their thesis in Word (or equivalent) and gave up in frustration, moving it all to LaTeX. I never knew anyone who successfully went the other direction. I don't know if that is still the case."
Ha! I started my thesis in LaTeX but my adviser only wanted a word document for reading it, so I had to go the other way :)
One person I knew gave up on word when it suddenly lost half a dozen figures they no longer had the originals for. Never did figure out what the mechanism was, but you bet they became more disciplined about backups.
I'm sure it's much more reliable today, but once you had a long document with a bunch of figures, tables, and equations in it, Word started doing odd things. Including just refusing input for a couple of minutes with no message, then crashing. Good times.
Some people use it for everything, but I think it really shines in writing documents with heavy mathematical content due to the straightforward math syntax.
There was a paper posted here a couple months ago that claimed that even expert LaTeX users wrote documents slower than novice Word users, but the interesting caveat is that LaTeX users were far faster across the board when the text included a lot of math.
You can easily solve versioning and collaboration issues because the input is plain text (like source code, just version control it and use patches, PRs, etc.) This works better than "track changes" in practice, especially with multiple authors.
So those are the upsides. Downsides: it's a bit esoteric, and clunky for lots of documentation tasks. The implementation is complex and the package/module system can step all over itself. If you have output that is nearly but not quite right, it can be a real bear to fix it.
These days Markdown may be a better choice for a lot of simple documentation tasks where you don't care much about the final output presentation details. Any word processor can probably let you do some things more quickly.
When I was a grad student I knew multiple people in STEM fields who tried to do their thesis in Word (or equivalent) and gave up in frustration, moving it all to LaTeX. I never knew anyone who successfully went the other direction. I don't know if that is still the case.
If you use it a lot, you may find yourself wanting to use it for everything (letters, resumes, presentations, etc.) but many of those things aren't particularly strengths. If you don't use it a lot you will find it hard to come back to casually.
One other strength I should mention, especially for automated documentation. Knuth was very particular about stability in TeX, and LaTeX has mostly-kinda-sorta followed this philosophy. So unless you have used a lot of marginal packages or something, it's entirely reasonable to expect that processing a 20 year old input will work fine using current builds. This is not something you can say of most systems.