Is it useful to get a link from a directory?
Directories exist for many years on the Internet. By the way, the search engine Yahoo was a directory before it became an engine.
However, these services supposed, to help users finding answers to their questions at a time when search engines were much less sophisticated have mostly become SEO tools. Sometimes even tools created by and for SEO professionals in order to generate links.
Indeed, they make it possible to get a link in a simple and fast way.
From Google's point of view, it is therefore a way to artificially increase the popularity of a website. Yet numerous directories are very well ranked in search engines!
Many tests have shown that links coming from directories are still beneficial today. It is up to you now to distinguish the "good" directories from those considered as links farms.
Anyway, you will have to take time to write an original content for each directory in order to not undermine your efforts from the start.
A link in a topical directory can be a lot more impactful than a link in a too general directory.
As time goes by, the visibility of directories tends to disappear. Check whether the directory is well ranked on Google or not in order to know if it is interesting.