I'm not going to spend too long on this one since most everyone has seen it and you already probably know what to expect. Yes it's a really fun ride but to avoid wandering down familiar alleys I'm just going to pick out a few things I liked and a few things I didn't like.
Likes: Fun characters, fun story, lots of crazy plot twists, spectacular anime quality, fun setting, fun characters.
Dislikes: Lots of battles (way better than most battle heavy anime though). That's mostly it. I just really enjoyed this one for what it was. Sure it's nothing ground breaking story wise, but you can just sit back and watch it.
When this season ends if you've finished you'll likely be dying to watch season 2 which while controversial is also a great ride. Again, just enjoy it for what it is.
Code Geass was again one of the first animes I watched and again I'm glad I did. It's shows of this nature that allowed me discover that there was something of value in anime that I'd been missing all these years.