As a developer / devops engineer, I can't think of anything I found good or outstanding in the Sitefinity product, I feel it falls behind its competitors in the majority of areas. If I had to pick an area I think that was the best part of the product, it would probably be feather (but even this lacks in many areas). Review collected by and hosted on G2.com.

The page based architecture (unlike umbraco / sitecore being more of am item based architecture).

The need for a lot of magic strings to make it work and gave poor error guidance when it didn't.

Building an atomic design was near impossible

Content being (generally) limited to a single widget (whilst reusability is possible, it is annoyingly complex to achieve)

The price tag (considering there are better cms' for less money imho)

The promotion pipeline

The lack of community add ons / support Review collected by and hosted on G2.com.