The site is, obviously, beautiful. I have already faced some frustrations, almost all due to bizarre UX choices when it comes to automatically closing content.
The "Onboarding Checklist" is fun, but it's not always obvious how to proceed. At one point it said it was going to give me a tour of the interface, then popped up a single hint about creating a task in the top right. It didn't clearly instruct me to create a task, and I didn't particularly have one in mind. So I closed it, which closed the whole tour. There was no obvious way to resume it.
When creating a Space, a New Space modal pops up. I filled it out with a Space name and description. Then, I saw "Use Template", so I clicked that, which shows a bunch of themes. I decided I didn't want to use a Template, so I closed the Template modal, which also closed the New Space modal, losing the Space name and description I had previously entered.
I find it crazy that clicking anywhere on 60% of the screen can lose work/input without any warning. It turns out, this auto-closing modal behavior is something of an anti-pattern at this point: A quick Google search suggests a lot of developers are ditching it. I would be happy with a setting to turn it off.