Here are some advantages and disadvantages that came to my mind:
Advantages
- can be deployed on every server, as it's just static html
- has partials, that can be reused, in contrast to normal html, where you have to code/copy paste every thing
- you can still code in an IDE
- a non developer can edit code (sometimes at least)
Disadvantages
- the template language is limited and sometimes a bit awkward/needs to get used to
- you have something new in your environment, which has additional costs (more than one developer needs to know how to build the site, ...)
If you know your current toolkit well and you do not have a problem hosting another ASP.net project on your server, I do not see the need for you to introduce another tool in your tool chain.
If you want to do something, where users can generate content - like github does on the github pages - this is something you might consider.
As for Jekyll, we tried it on one project and being devs, who like to code, we ran into it's limitations quite early. You can work around this, but if you know a programming language you will be faster. It was still fascinating, how far we were able to go with just using Jekyll