Hi Lexi,
I didn't do the NOLS semester, but I did the NOLS 30-day Backpack/Canoe course last summer (2010) and loved it. I also live in Yukon, so I am a little bias, but I can let you know that the scenery is amazing! The Yukon has lots of diverse characteristics, including magnificent mountains and tons of lakes and rivers. The semester program looks great because you really get to explore all these areas and aren't limited to one type of terrain. You get to climb, paddle, hike etc.. I know I'm extremely jealous of where the group last year spent their time (flying in a float plane, mountaineering, canoeing), especially when I returned home and I knew that there were still groups out there!
In terms of the NOLS programs - they know their stuff and will make sure you are prepared for the course. The Yukon does have some harsh climates, so be prepared for all/any weather! I'm sure you'd get a taste of everything the Yukon has to offer over the whole semester.,,but NOLS make sure you have the right gear and will teach you the leadership skills to help you along the way..One of my favorite things was getting creative with the food (backcountry cooking) and getting to know 15+ other individuals. The people that the Yukon courses attract are really amazing and it's the friendships that you build during your time that will really stick with you.
Maybe check out Facebook and Flickr for some pictures, there might be some from past years that will give you a good sense of what to expect.
Best of luck,
Lia Johnson