1. Flexibility of blocks is a cognitive overhead for most folks in my team. They would rather prefer more constrained and opinionated approaches like Trello
2. Notion is currently a jack of all trades and master of none. We have tried to use it as a wiki, project tracker, issue tracker, CRM & spreadsheet. Though it's good to have one tool that can do many things, we quickly reach limits of what is possible automatically and have to spend a lot of time to manually maintain it
3. Convention over configuration creates problems for other team members to follow because conventions are not documented properly.
But I see a lot of potential of it becoming a platform. If they can incentivize 3rd parties to build over their platform and build trust, I think it's gonna be the next big thing. "One platform for all my data" with specialized tools to deal with different kinds of data. I can imagine tools like Tello, Jira, Hubspot, Google spreadsheets & draw.io running over it.