I've used Wordpress a bit but as a bit of a nerd I was really excited to hear about the Ghost blogging platform, which is new and shiny and uses node.js which I really like.
Wordpress is php based, which can be okay if tuned correctly and all but I personally found it rather slow. Also the plugin scheme is all php based, which I am not crazy about. Again it's not bad, but it's a server side, web 1.0 style of plugging in.
On the plus side, Wordpress is really mature, and there are gobs of themes, plugins, etc for it.
Ghost uses node.js which I like for several reasons:
1) It seems much lighter on resources - even when fronted with nginx
2) I already have node.js on my servers
3) Node.js has a huge and very enthusiastic eco-system
What I like about Ghost in particular, is that it's very Web 2.0 - clean UI, uses client side templating, has REST APIs built in.
But as of this writing, there are a few things that make it a non-starter for my needs (your needs may vary, this just my perspective):
1) The editor has no real UI for formatting - I was expecting at least a few basic controls for bold, italic, insert link, etc. - but right now it's all text based (Markdown). I personally don't mind Markdown, but I can't expect everyone that goes to my site to know Markdown. It's a barrier to entry I can't afford. I know, once you learn it it's great, and it's pretty easy to learn, but it still won't work.
2) The multi-user admin support isn't in place yet. This is key for my needs. As I understand the underlying code is all setup to be muti-user, there just hasn't been time to develop admin UI for it yet. Per the roadmap, this is coming in version 0.5 in the July 2014 time frame.
3) There aren't any plugins yet. If I understand correctly, the plugin API is pretty much done now, but it might be a little while before plugins start showing up. There are at least themes now in the Ghost Open Marketplace, and eventually that will have plugins too.
I think all of these are surmountable, and I'm fairly certain the multi-user admin and plugin repository will evolve. They do seem fairly opposed to having UI controls for editing, but I'm guessing either there will be a 3rd party plugin for that or they will add something in Ghost itself - I think it will have to have that for widespread adoption personally.
If it's for yourself and you are comfortable with Markdown though, it's worth a look for sure. But if you want to install a blogging platform for multiple users, you may want to wait for the multi-user support and for the plugins to start coming on line.
Anyway, that's my take on it!