Just had a look at the YouTube video linked through that site, looks like an awesome route and like you said nothing looks to daunting hill wise. Hope you have fun and good luck!
On a related note in the recommended videos after watching that came up this little video, some drivers really are idiots.
Gnarrr.
Went OK today, better than expected, went out quite easy not knowing how I would go with the distance, tried to stick in a group, but at the slower end of the field it tended to split up a bit more.
I was finding the hills a lot easier than most people seemed to, passing people all over on the climbs, some would come back past me downhill, not sure how, heavier rider perhaps or bigger gear!
Got to about 40km, my left leg felt like it was going to cramp, I managed to bunch up with a couple of other guys, we got to 50km and this turned into a bunch of 6. Then it was time for a world of pain

35-40kmph all the way back pedalling for my life, had to take turns at the front which was a total killer for me and a real struggle, was just trying to hang on at that point! Much more fun riding in a fast group though, will have to try and get to the local club.
Waiting for the official result, but I timed myself at 2 hours 17 mins for the 70km, with an average of just over 30kmph which is the first time I have been over 30kmph average!
http://www.endomondo.com/workouts/50021780
I really struggled with back pain when I got off though, couldn't bend over at all, had a hot shower and stuck some ibuprofen gel on.