Benign it`s very flat indeed. Only slight incline is the up section of an underpass at 37 ish km as mentioned by Eggy. Unpleasant at that stage of the race but manageable (actually I found the downhill into the underpass worse - harder on the already pulverised quads).
I`ve done it a couple of times and on both occasions got clobbered by the breeze/wind coming back along the Amstel.You`ve got 13 miles under your belt by that stage so fatigue is just peeping around the corner. Apart from that - it`s a fast course. The start gets congested; it`s bleak and low on support through the industial area - but that only lasts a few miles - and the finish is great.
Betzza Vondel Park area is nice. Quiet, civilized but a shortish walk to the city centre and a shortish walk to the start (depending on which end of the Vondelpark you stay in).
AirBnB has a few properties left in that area so might be worth getting something sooner rather than later.