I used it a bit recently and it is brilliant. Instead of lugging a huge TeX installation around you have a single reasonably sized binary. When you run ’tectonic file.tex’ it will download everything it needs on the fly. If you want to run it without internet access you can sort of freeze the downloaded files and run tectonic with your *.tex plus the frozen bundle.<p>It also claims reasonable error messages but I only ran it on error-free files, so I cannot tell.<p>One small downside is that in my direct comparison with lualatex it was always marginally slower.<p>Another one is that it is not a rewrite but still based on the old TeX code.<p>I think tectonic is a great project but generally speaking I find it quite disappointing that we do not have 100% compatible LaTeX with a modern codebase. And that is not even because the old code is bad - not at all. It's just that a pure Rust or Java implementation would make it so much easier to integrate into other projects. An audited TeX core we could run on untrusted input would be another benefit.<p>Which brings me to my last point: When researching tectonic I found a fork that attempted a pure Rust port and it <i>nearly</i> worked with examples. There is hope...*