About 20km from Penticton is a short, steep climb up McLean Creek Rd. I think that this is the steepest climb of the day but it's really short. Apart from that, the first 60km to the base of Richter pass in Osoyoos is fast, net downhill often with a tailwind. Very tempting to hammer but probably not the best idea :)
Richter, as AP said, is neither steep, nor particularly long. It's also broken up into three pitches so you get a bit of a rest in between.
IMHO, the real meat of the race is what comes next ... a series of fairly significant "rollers" often with somewhat of a headwind to overcome. The out-and-back near Cawston is also rolling and generally rolling. If you've ridden conservatively to the top of Richter, you will pass a lot of trashed-looking people in this section. After the out and back, there is a gradual climb (a false flat really) from Keremeos to the Apex turnoff where the Yellow Lake climb begins in earnest. Yellow Lake on race day is awesome - it feels like something out of the Tour de France with all of the people lining the road. It's steeper than Richter but really not that long.
Once you summit Yellow Lake, the rest of the ride is almost all downhill. There is one little climb up to Twim Lakes but it's nothing. The free ride before you start the run is just awesome!!
Check out
http://www.ironmap.com/ for a great look at the course.