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 the author having written a very nice book in LaTeX, is entitled to his views and has some valid points. I agree with some of them but disagree with most of them.
He has valid points on ease of use and the lack of a GUI. However, he misses the point that to incorporate the 100s if not thousands of commands available to a user via the basic TeX engine, LaTeX and the few thousand available packages plus an author's specific macros will provide the most complicated and frustrating GUI possible. It will also not be quicker to find these commands. A GUI works well if everything is available two clicks away, anything deeper and you will battle to find it.
Spell checking is provided for most users via the editor. Grammar checking never worked in Word and is a frustrating experience to have to deal with it.
Figure placement has never been a serious issue for me, neither getting them at the top 20% of the page (see for example https://tex.stackexchange.com/a/35162/963).
I agree with the author that fonts and tables are difficult to use. I don't see an easy way out on tables, but font management could certainly be improved.
I disagree on his comments for hyphenation and index production. I actually view these as part of the strengths of LaTeX. I also disagree on his views of firstly the importance of micro-typography and secondly I have doubts in line with Joseph's comment if he actually was referring to grids or micro-typography as most of us understand it.
He has valid points that LaTeX out of the box does not follow typographical trends. The problem with typography is that it is a very broad term and like fashion it changes. Where typographical rules could be deduced Knuth did incorporate them. He also set the standards for mathematical typography.
If the author can define the
typographyrules, I am sure that he will end up with a number of styles. How do you define typography for a glossy magazine, a photography book or a dictionary? If these rules can be deduced, they can be programmed fairly easily.So is there no room for improvement? I think his idea of funding is good. I think from a user point of view multi-column layouts are not what they should be. There is huge room for improvement here. Font management can be improved and perhaps simplify the user interface. The LaTeX3 project needs to give serious thought to a syntax that I am sure will not go well with programmers. A sugary super-set of all commands will be necessary. Thought should be given by the community in developing more templates and classes rather than packages.
Having said all that I need to add, that I have seen and used all the word processing packages from HP specific packages, wordperfect, all versions of word etc. and I have been with (La)TeX since my student days and that is a long time ago. You sacrifice a few things, but (La)TeX also gives you stability. You also don't throw away your knowledge but rather add to it with the years. The only program that now competes with LaTeX is Adobe InDesign. If you are prepared to write your pages using LaTeX, page by page (similarly to a graphic designer) or the way web pages are developed you can achieve the same if not better results.