I am using it since several years and I have yet to find the caveat :-)

It has low discoverability, so you have to go through the manuals, the mailing list and the forum (and maybe the blog too, at https://texmacs.gitee.io/notes/docs/main.html) to figure out all that it can do, and to have complete control. On the other hand, it is quite usable with default settings.