Sadly they focussed on the beautiful GUI above upgradability of the debs. It lags behind actual Ubuntu by at least one Long Term Release (possibly 2 by now if they still haven't upgraded from 2012) and I've found it a pain to work with beyond the initial "wow this is pretty for Linux".
(I actually ended up using XFCE and then AwesomeWM, so maybe I'm not the market for Elementary!)
EDIT: just checked and their newest release, Loki, is based on Ubuntu's 2016 LTS. I'll be taking another look at it this evening!
eOS is something I would probably recommend to my mother or my girlfriend if I wanted to give them an easy "introduction" to Linux. But the designers made several decisions that seem hostile to power users (you can't even add your own PPAs in Loki by default), and for that reason I'm not sure I'd recommend it to developers. Which I can understand, I guess--I've mentioned my problems with it to the designers directly and have been more or less told by Daniel Fore that I am not their "target audience". So, okay, you can't please everyone.
The Pantheon desktop is beautiful, and it deserves all the praise it gets. I maintain hope that the eOS team will work on disentangling Pantheon from the rest of eOS once they finish stabilizing the core OS so that it can be ported to other distros. Ideally I'd eventually have Fedora running on my laptop with Pantheon strictly as the DE.
It's true, Windows and OSX are usually miles ahead of Linux in terms of the desktop GUI. But I absolutely love the simple beautiful UI in elementaryOS, it's a delight to work in. It is my primary OS on my laptop. I also has Windows 10 installed, but everything feels more instant in Linux. God knows what Windows does under the hood to make it that slow and unresponsive.
I installed the latest version (Loki) for a couple of months ago and except from 1 issue with "wobbling" mouse cursor (resolved by installing some xorg components) it works great.
I had some troubles with the previous version (Freia, I believe), more specifically the desktop manager would frequently hang. Luckily that haven't happened once in Loki.
All of the tools I use on my Windows box are availble for Linux as well: Netbeans, Jetbrains Pycharm, GitKraken, Chrome, Slack, Dropbox etc.
The only thing holding me back from switching primary OS on my desktop computer is gaming.
I use elementary OS Loki daily and am pretty satisfied with it. It has a few things that I'm not totally happy with, but it's my favourite OS right now.
(I actually ended up using XFCE and then AwesomeWM, so maybe I'm not the market for Elementary!)
EDIT: just checked and their newest release, Loki, is based on Ubuntu's 2016 LTS. I'll be taking another look at it this evening!