In short: A nice, flat course through some interesting parts of Pompey. Great for first-timers. The start was a bit congested though. In full: I really enjoyed today's run - the glorious weather certainly helped! Travel arrangements appeared to be well organised, though having my parents living only a 10-minute stroll from the start was obviously a bit of a bonus for me!
I've only done the Great West Run before today's event, and I found the Great South much more pleasant and easier.
Being very flat, I was hoping for a slightly better time than I actually achieved (1h 21m), but I blame part of this on a very slow first couple of miles due to congestion.
Also, I agree that some of the mile markers were very difficult to spot.
Overall though, I loved it and will definately be back (faster?!) next year.