I loved running chicago. It was my first marathon, after a summer in chicago, so the course was familiar. The crowd support during the race is phenomenal -- people every step of the way. I had trained poorly, due to an injury, and ended up near the end of the pack, but had people cheering for me every step of the way.
Being one of the largest marathons in the world, the expo was big and well attended. I was able to stock up on quite a few running things that I'd have to order online otherwise.

It's an expensive race, but the experience is worth it. The course support from both volunteers, spectators, and other runners makes the high fee worthwhile.

The shirts ran small, so order a size up. I was able to exchange mine at the expo, but thats not guaranteed.

The aid stations had both water and gatorade, and various energy chews and gels.

Overall, chicago is a really fantastic race in a really fantastic city. I would recommend it to anyone!