See my Strava route
I took a platypus. There was water provided after Mar lodge (about 7.5km) where you turn off the road and start climbing) and at Derry Lodge (about 13.5km). After that the only big water sources are Luibeg Burn and then on the descent at around 29km when you cross the burn.
The crossing at Luibeg Burn was fine last year - lots of big rocks to use as stepping stones. Nothing to worry about.
People mention the boulderfields at the Pools of Dee (26km) as being tough but I found them no problem at all - just look ahead for the small paths that weave between the boulders.
I struggled more with the continual rocky path from the Luibeg Burn to the mature forest in Rothiemurchus. Wasn't expecting to have to watch my feet for so long.
On the descent definitely fork left to get to the Cairngorm Club footbridge via a sharp left at Picadilly. It's a big step onto the footbridge when you're starting to cramp.
The finish is on the left hand side of the road in Aviemore so remember to cross.
I struggled with eating after about 2 hours - it was the first warm day for a month - and was suffering by the end.