I did the marathon as a training run so I wasn't aiming for a fast time at all. It is a great event and a good choice of you need to add some hill training into your training plan.
The event was well organised, the refreshment stations were well stocked and well manned, the marshalls did an outstanding job on the day and the course was well marked.
The marathon course is two laps of the half marathon course and I enjoyed both laps. The second lap wasn't busy after the half marathon runners had finished. If you are not mentally strong you would probably struggle on the second lap.
I'd definitely recommend the Southampton marathon as a training run,