Can't be much slower than PHP or Ruby, so theres that. What is repelling to me is callback-hell and Javascript as a language in general. People will build simple stuff with this, then it will evolve, and then someone will have to deal with it. I don't want to be that guy.
The concept is good, even though javascript is awful. I'm more in the direction of a Riak/Webmachine/Ember-Angular-Backbone-Batman-Knockout-Whocares/Erlang stack, though. There are many ways to execute pretty much the same thing as MEAN and avoid Node/Mongo, and new tooling on legacy projects to support the MEAN stack will inevitably also support other methods because that client-services model is so decoupled.
Can't be much slower than PHP or Ruby, so theres that. What is repelling to me is callback-hell and Javascript as a language in general. People will build simple stuff with this, then it will evolve, and then someone will have to deal with it. I don't want to be that guy.