I tried it about a year ago and I don’t know it did not convince me. Yeah it might be great for some niche developer oriented needs or deployment but for a normal OS usage, meh. I kind of see it as a current hype, just like crypto/NFT before, and AI now. For normal everyday usage I find openSUSE Tumblweed much more suitable and much more widely applicable.
A couple of months ago our company decided to standardise on only one GNU/Linux distro and they chose PopOS. While the default desktop is better then stocj GNOME it was still far away to what I am used from the powerful, featureful and customizable KDE Plasma so after about two weeks I switched to KDE Plasma (unfortunately they have an extremely old version in their repos, but still much better).
I can only guess that Cosmic will be on pair to their current improved GNOME but will still be way lacking compared to what even an old KDE Plasma offers. And I would also much more like to see if they put more attention to keeping more updated KDE Plasma and KDE software packages in their repo. Even for Cosmic I think they would be much better of basing it on the extremely flexible and configurable KDE Plasma base and make it a heavy modification of this.