It's honestly not as much of an issue as it's often made out to be. There are a ton of ways to manage asynchronous code out there including but not limited to all the various promise libraries such as when.js(https://github.com/cujojs/when), q (https://github.com/kriskowal/q), and bluebird (https://github.com/petkaantonov/bluebird). Not to mention the Async library (https://github.com/caolan/async) which is full of tools to help manage it.

As for blocking, it's something you deal with. Realistically speaking if you're doing CPU intensive tasks then Node is definitely the wrong solution. However, if you're doing tasks that are IO oriented then Node is fantastic.