This is the first time I've built a computer for myself (I've done a few for the family business). Setup was pretty much a breeze, aside from the 212 being a bit of a pain to install. Everything worked the first time.
I'll be mostly using this for gaming, but also a bit of After Effects, animation, and maybe some 3D modeling on the side. It's only been in use for a day, but it can run Bioshock Infinite on max settings beaaaaautifully. Haven't checked the FPS, but it's buttery smooth.
Haven't tried any OC yet, but I plan to do a little in the future. No need yet, though.
Only minor regrets I have are the memory and the PSU. Memory, thought I was getting a good deal on it, but 1600 is the same price pretty often, so not so much. PSU, I just haven't heard great things about OCZ. But I haven't had any trouble from either component yet.
In the future, I'll probably upgrade my memory to 1600/1866, perhaps expand to a multi-monitor setup, and get some real headphones (these were $10 after rebate - they get the job done, but eh). Wouldn't mind getting a Ducky, too (though I'm loving the Trigger - it's my first mechanical keyboard).
Edit: Forgot to add, the $1200~ was for the base components, while the peripherals + OS added up to the total of $1500~.