i actually went through this debate a few days ago when deciding what to use for realtine updates on our new platform. I had previously used socket.io but decided I'd try just using straight websockets and not bothering backporting realtine updates to IE9. Really great decision IMO. The basic Websocket API is actually really easy to use. i got everything up and running in less than a day, the server is less than 100 lines, and the client side code is about 50 lines and completely resuable and DRY wherever i need realtime updates. Compare this to the 100kb (minified) and all sorts of boilerplate you have to write for socket.io, so in my opinion you're better off with straight WebSockets these days.
That link mentions that it's both a server and a client, which made me realize i didn't mention what i used server side. I used https://github.com/sitegui/nodejs-websocket/blob/master/READ... which is extremely easy to set up and use. i don't doubt the value of socket.io but I for my purposes it was not optimal.
i recently made a messaging app something like appear.in using websockets in less than a day. Just added nodejs cluster support to it. Kind of easy to learn and easy set up made me love websockets.
