I'm trying to decide which set of macros/typesetting system to learn. I tried Latex2e for a while, but I was very disappointed that it didn't work nicely with Unicode and that in my tryout I had many classes of packages.
Now I'm trying ConTeXt, and so far I'm really liking its unified philosophy and how it uses parameters. The problem is, how I'm supposed to work with it (or even learn it) if the most recent documentation is more than 10 years old?? Is there another source of reference?
The ConTeXt documentation is a bit scattered and part of it is outdated, that's absolutely true. A good point to start is the revised ConTeXt user manual and for the graphical part the MetaFun manual as well as the ConTeXt wiki. For a more in-depth view you can have a look at the various manuals on the Pragma ADE site. However, many of them are outdated, or at least contain outdated information.
When you start with ConTeXt I suggest to stick to the MkIV version (compile with “context” instead of “texexec”). It uses luatex internally and has thus no problems with unicode.
Another (the most important one?) very valuable source is the ConTeXt mailing list.
Also have a look at Where can I find good ConTeXt documentation.
context instead of texexec to compile your documents it is also fine to start with the “ConTeXt excursion”, if you prefer a shorter version. If you then run into problems have a glance into the revised manual, the wiki, TeXexchange or the mailing list.
Your answer: ConTeXt's syntax has remained amazingly stable in these last 10 years. I learned ConTeXt using the same documentation you mention, and only discovered the age of the documentation after it had already taught me ConTeXt.
Jump in, don't be afraid; the manual might not mention all the newest features, but what is in there is practically all still valid.
First, don't bother with mkII unless you really, really have to. But I'm sure you don't. I would suggest such curriculum using what we got now:
