I won't be using Deno. For starters, I like javascript, not typescript, and I think Ryan was considering the idea of making Deno TypeScript only at one time. That is enough for me to never consider it alone.

I think it falls into the same category as Koa (TJs successor to Express) and the upcoming "Rome" project. Someone creates a successful open-source project and then at some point in the future decides to make a better one with questionable tangible benefit and various downsides of its own.

The downsides I can see of Deno so far are that it is slower than node, it is not compatible with any server-side node code because it has rewritten the standard library, and it is inspired and based on the Go standard library, seemingly using Go idioms and so on.

Its benefits are questionable, vague, and not really proven.