Where I find Hugo lacking though is I have found it very difficult to theme. Hugo has a very particular way of doing things with sections, sub-sections, leaf nodes and branch nodes, and a very particular folder structure where having an index.md file does one thing, but an _index.md file means something totally different. This would be fine if the docs were extensive and explained this clearly but they are very light in this area and most knowledge seems to be burried in individual disqus posts and other people's heads. I am sure it makes sense to people already familiar to Hugo, but trying to grok it all as a new-comer has been difficult.
As a result working out how to do even trivial things such as listings of pages in grandchild-directories, or even just having a list of child pages with other textual content has been a terrible struggle for me. Existing themes are invariably horrendously out of date, so trying to learn from those is also difficult. To this day on my site, if you go to specific directory paths there is literally a blank page because for the life of me I cannot work out how to make Hugo display just a simple list of posts in grandchild directories. It is infuriating! Perhaps it is my fault for wanting a semantic directory structure (e.g. domain.com/subject1/subject2/actualContentInHere/ and the pages for subject1/ and subject2/ are literally blank).
TL;Dr - good but if you want to do more than CSS tweaks on an existing theme then you're in for a challenge.