I've never used OS X a day in my life.
The MacBook Pro is a fantastic machine. The screen looks great, it's made of glass and metal, and years later the performance has kept up. I have a Model A1398 with a retina display and thunderbolt ports from late 2013. The moment I got it I installed Ubuntu 14.04 and haven't looked back.
Apple isn't concerned with Linux compatibility so a few proprietary drivers are necessary to get the important stuff working.
Once you boot up you'll need to plug in an ethernet adapter. Once online install your updates, open up "Software & Updates", and install the latest proprietary closed source drivers for your Broadcom WiFi adapter and your nVidia graphics chip.
There are also a few other little problems to fix...
The track pad will freeze up randomly from time to time. Just install this.
sudo apt-get install xserver-xorg-input-synaptics
The laptop won't suspend when you shut the screen. Haven't found a great fix yet. For now I just hit the command key, search for "Suspend", hit enter and then shut the lid after it's suspended. Not ideal but not the end of the world either.
Also the webcam doesn't work. I consider this a feature. If you really care these guys have been working on a driver.
It's not perfect but at least it's Linux!
I'll keep this post updated as I find easy ways to fix the little problems.