Compare against existing libraries in README.md

Author: nhooyr

README.md

@@ -13,3 +13,32 @@ This library is in heavy development.
 ```bash
 go get nhooyr.io/ws
 ```
+
+## Why
+
+There is no other Go WebSocket library with a clean API.
+
+Comparisons with existing WebSocket libraries below.
+
+### [x/net/websocket](https://godoc.org/golang.org/x/net/websocket)
+
+
+Unmaintained and the API does not reflect WebSocket semantics.
+
+See https://github.com/golang/go/issues/18152
+
+### [gorilla/websocket](https://github.com/gorilla/websocket)
+
+This package is the community standard but it is very old and over time
+has accumulated cruft. There are many ways to do the same thing and the API
+overall is just not very clear. 
+
+The callback hooks are also confusing. The API for this library has been designed
+such that there is only one way to do things and callbacks have been avoided.
+
+Performance sensitive applications should use ws/wscore directly.
+
+## [gobwas/ws](https://github.com/gobwas/ws)
+
+This library has an extremely flexible API but that comes at a cost of usability
+and clarity. Its just not clear and simple how to do things in a safe manner. 

ws.go

@@ -27,6 +27,7 @@ func (c *Conn) NetConn() net.Conn {
 // MessageWriter returns a writer bounded by the context that will write
 // a WebSocket data frame of type dataType to the connection.
 // Ensure you close the MessageWriter once you have written to entire message.
+// Concurrent calls to MessageWriter are ok.
 func (c *Conn) MessageWriter(ctx context.Context, dataType DataType) *MessageWriter {
 	panic("TODO")
 }