TeX is both a program (which does the typesetting, tex-core) and format (a set of macros that the engine uses, plain-tex). Looked at in either way, TeX gives you the basics only. If you read the source for The TeXBook, you'll see that Knuth wrote more macros to be able to typeset the book, and made a format for that.
LaTeX is a generalised set of macros to let you do many things. Most people don't want to have to program TeX, especially to set up things like sections, title pages, bibliographies and so on. LaTeX provides all of that: these are the 'macros' that it is made up of.
As this question is unanswered so far, I will try my best to answer it. But I think, that because the way the question is worded, that no definitive answer is possible, so my answer will contain some portions that reflect my own opinions.
Also - as Joseph Wright pointed out in the comments - you may want to have a look at Why should I use LaTeX? and What professions use TeX/LaTeX besides CS?.
(La)TeX is great for producing texts while concentrating on the content and without too much distraction from caring about design. LaTeX can have a neat design, but the main focus is on producing text. So for essays you should be fine. Be warned, that LaTeX is not totally easy to learn, if you have to get ready an essay for tomorrow, don't try to learn LaTeX now. But if you learn it, you may save time later, because you can make all your essays with the already predefined macros and style.
You also talk about graphic design, and that may be a little more difficult. While LaTeX is able to make nice designed documents, most designers prefer to see direct output. That means, if you change something in your design-program, you see an immediate effect on the document. In LaTeX you always have to compile the document first. So, if you already have a license for a design-program and seem to able to use it, you may better use that for your design-work.
Is it worth learning LaTeX? In my opinion yes, especially if you produce many texts: reports, books, articles. What kind of people doing different subjects/occupations use it, and why? Hard to say, who uses it, but it is clear, that LaTeX seems mostly be used in science. Why? I think, everyone has another answer. For me is it the focus on the content, and doing design other days. I can even separate styling-issues in different files than the content. If I already had a solution for look for one document, I can simply copy/paste it into in similar document for same look. And as LaTeX uses simple text-files, I can use all programs for working with simple texts, from Unix command-line tools to version control.
Best Answer
I think a resume is more typesetting than word processing, so I would not use MS Word or OOo Writer. One could use Indesign or a free layout program.
Often resumes contain text in columns. Text in narrow columns is hard to wrap--TeX does a good job here. For even better justification use
microtypewith pdfLaTeX. I think with microtype the chance to avoid big gaps or lots of hyphenation is better than with word processors.It's good if the resume matches the covering letter. Since LaTeX is great for letters, for example with the scrlttr2 class, it would naturally be a good choice for the resume.
There are specialized LaTeX classes. Though I prefer a class matching the class for the covering letter, such as scrartcl together with scrlttr2. tabularx does already good work then.
A resume can be used for many years in your working life, it will grow with the time. LaTeX is stable and remains mostly compatible, so you can reuse your resume when you apply for the next job in 10 years. Imagine, you would have used Works or Starwriter many years ago... you would require old software and an old operating system to reuse an old word processing document. With LaTeX it would be much easier.
ConTeXt, which is based on TeX, gives you even more control over typesetting.
On TeX tips, written by John D. Cook, I found a link where Dan McGee shares his experiences:
Why I do my résumé in LaTeX
LaTeX résumé Follow-up including a template and an example pdf
While looking what others say to this question, I found Matthew M. Boedicker's Tips together with links to resume templates and examples on