It is very rough to use and clearly needs work before being released publicly. This is clearly an alpha version.

On-boarding:
The on-boarding does not exist so using it takes some time to figure out. It's easy to get work spaces confused with channels and it isn't very clear how to create channels. When you need to access the channels properties it isn't very clear how to access it. Similar confusion could be found using other features.

Voice Call:
They place a grey box with the user's email address instead of using something like an avatar system for voice calls. It isn't clear what's happening or if you are in a call. There is no sound effect or calling ring tone. Just silence and a grey box with the email address toss in the top left. When I pressed the leave button it just simply didn't work.

Performance:
Every tab seems to take longer then it should to load which does point to some performance issues. With simple UI they are using i'm surprised at the loading times.

Every feature is in an alpha state and needs work to improve performance, UI design, and usability.

It is way to early to release this. The features are there, they work, but really need some polish before I would considering buying it.

I loved the concept but need to give the product 6 months before I'd consider it at least usable.