I really like it. Startup times are now better than node (if not as good as bun). And being able to put your whole "project" in a single file that grabs dependencies from URLs reduces friction a surprising amount compared to having to have a whole directory with package.json, package-lock.json, etc.
It's basically my "need to whip up a small thing" environment of choice now.
It uses web workers on a web browser. So is this Deno Sandbox like that, but for server? I think Node has worker threads.