I did it last year - my thoughts are:
Fast course - pretty flat and a start and finish on the track
Not terribly inspiring scenically but you do go past the stadium (and all the support) twice so that gives you a buzz
Starting all those people on a running track means it's very, very slow at the beginning if you're near the back (we weren't, but as we left the stadium after 3/4 of a lap there were people who'd hardly moved)
For those that are bothered about that sort of thing the goody bag's a bit crap - low quality t-shirt and some leaflets