Recs.
Updated
Latex is a markup language, that also handles typesetting.
SpecsUpdate
Pros
Pro Effortless math input
The whole reason that TeX -- and, by extension, LaTeX -- exists is to give people an easy way (well, for some value of "easy") to produce high-quality documents with properly laid out mathematical expressions and text in them. As long as you know the language (or have a reference sheet handy), you can include mathematical expressions in your document with little to no extra effort needed on your part.
Cons
Con Single-threaded design
LaTeX is single-threaded by design, since it must necessarily work sequentially to produce each page as it is laid out by the typesetting engine. This makes it dependent on the power of just one individual core in your multi-core computer setup and so migrating to a machine with more cores won't necessarily make your LaTeX documents build faster.