HCL Domino (formerly IBM Domino, and before that Lotus Domino) is an enterprise application development platform, boasting mobile-app capabilities to enterprise authentication and a companion low-code app builder called Domino Volt.
Domino is secure by comparison, due in part by it's lower market share, but also it's native encryption capability. Domino is stable. With fewer changes and revisions, Domino performance can be relied upon with existing infrastructure. Despite its clunky admin console, administration as a whole is easier and more intuitive. The native Domino application language is either Java or LotusScript. Finding developers for the latter application can be troublesome.
I am not a fan of the Domino ID for authentication purposes. Some Admins appreciate this feature, but ID aging, updating and management issues are burdensome.
Integrations with current available software applications as a result of lower Domino adoption rates.
Administration tools are somewhat dated and clunky. Even with updates and patches, the Domino administrator console hasn't changed in years.
We use SharePoint, SQL and Teams but only for the things that they excel in. For example, we use teams for small team interactions (including external participants). We use teams for meetings too. We've discovered that Teams collaboration is not as full-functional as Domino and more importantly, that our members (financial services) do not trust the Open Office365 cloud. SharePoint and Team collaborative features are often blocked in our member organizations. Domino is much easier to identify and unblock at the firewall level. It's much easier to restrict collaboration to approved options in Domino.