I've not run this course before but I have run half of it (in reverse) at the Paris Half Marathon in 2007 and 2008. I always like running in Paris and this should prove a good one. In the past it has been accused of not being well supported by the masses but the scenery should all but compensate for that.
I've only ever run marathons on French soil and have found them to be well put on and well supported evets with great aid stations. But the one thing you CAN NOT predict is the weather. I have been burnt on my last few sorties even though rain was predicted.