Mine came the other day (the base model is only like $35, and you can get a "kit" with everything you need for around $60) and I've been messing around with it, getting things set up the way I like.  There *is* a bit of work involved, some command line stuff in the terminal, etc etc, but it's fairly intuitive for newbies like myself.

(*note: legally speaking you're not supposed to download ROMS for games you don't own).  <----  Just thought I'd mention that.

Anywho, even though I'm a retro game collector and own pretty much all the older consoles and hundreds of games, it's pretty cool to have everything on one tiny console that you can just play whenever you want.  

SO, any of you have this set up, or maybe plan to check it out?

Here's a tutorial:    http://lifehacker.com/how-to-turn-your-raspberry-pi-into-a-retro-game-console-498561192

I actually just set up my RetroPie last month. I wrote a blog post on it at my blog: My Retro Pie

I really like it. I tried using an Ouya in the past, but the lag on it killed me. The RetroPie is simple to use, has no lag, and works great. I love that its small and can run so many systems with such an awesome user interface. I highly recommend anyone whose into retro gaming, but can't afford it. It does take a little computer know how, but there are some great tutorials that'll walk you through everything.