I have some previous experience with WordPress, though never liked it, but chose Ghost over it when starting my own developer blog (this one). My blog is now about one month old and having no previous experience in Node.js or even Ghost, after writing my own theme and configuring it, I think I can now say what I learnt, what I liked and what I don't.
Ghost is fantastic! From installation to running, from writing articles to theming, everything is very intuitive.
The installation is somewhat confusing, I can't deny, if you have no previous experience, but you master it after 3 or 4 failed attempts. Then, installed, everything is comfortable to use. Post editing markdown is very very very practical, unlike WordPress and its buggy text editor. Just putting a # when starting a paragraph gives you a header (html h1) text. Put two (##) and its a smaller one, h2 header, and so on.
There's also a hint button on the bottom-left showing how to use markdown, if you miss how to post a link or a h1 header.
The back-end is also pretty straightforward, thanks to a small slide menu. It holds 6 configurations: General (for site-wide configuration), Navigation (some settings for site menus), Tags (obviously, for managing post tags), Code Injection (a very useful tool to inject html code natively, instead of hardcoding theme files), Apps (currently has just one app, Slack, but more is to come) and Labs (for beta features).
Talking on back-end, Ghost offers natively cache and runs pretty fast thanks to its node.js engine. Also comes with SEO tools for free, out-of-box.
Though very intuitive and fast, Ghost still lacks one feature where WordPress shines: plugins.
The community is trying to reverse this trend, by implementing some integration with APIs but, for now, the only thing you can do is to set a bot to publish new posts to a Slack channel.
Besides lacking plugins, Ghost also lacks themes, both paid and free. A first look at Ghost Marketplace may show the opposite, but if you look more closer, themes there aren't that creative and tend to look somewhat generic. I found myself in this dilemma when setting up this blog and ended coding my own template (which you can now download for free on Marketplace).
Updating, too, is a painful process. Look this: You have to follow 12 counter-intuitive commands just to upgrade your installation. No SSH? No updates. At least, Ghost will not break all your site by updating it, instead of WordPress, at the cost of typing a list of commands prone to break sometime without much debugging information. Even worse, this discourage people from updating their blogs, spreading vulnerabilities through web.
That said, if you're a tech-savvy user willing to discover new worlds while setting up a blog or a firm with a competent IT sector, Ghost is a good choice for blogging or news publishing. It's stable, fast, won't leak memory and comes with caching and SEO capabilities out-of-box.
It's also ok to say it's safe. Being a new platform, with a very few niche users and built on top of new technologies, Ghost isn't prone to suffer the security problems WordPress has suffered the years before. Looking at this perspective, lacking plugins can be a pro, as WP's most security issues come from badly coded plugins.