I love it. Technic is one of the first mods I install whenever I set up a new world and it is also one of my go-to mods when I just want to toy around with things. It is very feature-rich and well integrated with a lot of other mods.
… but: it entirely lacks of proper documentation.
The wiki on GitHub has pages that were last touched almost 10 years ago and basically contain nothing more than the name of an item or sometimes only a list of headings. There is also a “manual” wich is an unsearchable giant wall of text without any proper information on crafting, alloying (what materials in what ratio), and other things to produce stuff.