Flexibility is the biggest strength. Notion can be shaped for almost any use case: wiki, PM tool, CRM, documentation, personal note system. Teams that know what they want quickly arrive at a setup that works.
The low barrier to entry helps with adoption. New team members understand Notion in hours, not weeks. That is different with tools like Confluence or Jira.
Notion has a clean REST API and recently also an official MCP server. This makes Notion an interesting building block in automated workflows: read data from Notion, create entries automatically, synchronise databases with external systems. Those using n8n or similar tools can integrate Notion seamlessly.
Many developers use Notion as a personal knowledge base. Snippets, documentation, resources: all versioned and searchable. Outside of work we also know some who build their private knowledge database with it, from book notes to recipes to travel planning.
And: Notion is available as an app for iOS and Android. Mobile works well for reading and quick notes, for more complex database work the desktop is more comfortable.