I use Hugo for one of my side projects' static sites, and actually just today migrated from using HTML templates to Ace. (I also use it for my blog.)

My pros and cons of Hugo:

+ It's fast.

+ Like, really, really fast. I'm looking at <1s builds for a couple thousand pages which took around 5-8s in Pelican.

+ A lot of really nice out-of-the-box stuff like markdownifying arbitrary strings, rss and sitemaps, etc.

+ Extensible front matter system. (I abuse it to stuff an arbitrary JSON object into each page.)

+ Did I mention how fast it was?

- Debugging is hell. Error messages are unintelligible and generally distract from whatever the actual issue is.

- The structure of a theme is sort of unintuitive, but that may be personal preference.

- Lack of support for more user-friendly templating languages like Jinja2 (this is likely due to speed, but I'd still like the options.)