From the official announcement https://groups.google.com/forum/m/#!topic/nodejs/fqBTNLwhEAI

    The main advantages/differences over Connect/Express at this   point are:

    - Patterned after WSGI/Rack. This implies some significant differences in the API.
    - Built on node 0.4; takes full advantage of streams.
    - Built-in support for streaming multipart parsing/file uploading (uses node-formidable's parser).
    - Built-in support for gzip encoding, URL rewriting, and URL mapping.
    - RFC-compliant support for content negotiation using the Accept, Accept-Language, Accept-Encoding, and Accept-Charset HTTP headers.
    - A specification with middleware to enforce it.