Lots of good tips here. Bundle them up and they will be fine, as long as they enjoy it. I have two kids (3.5 and 1.8 yo) and now a double Bob. The older kid doesn't like it much ("Dad, I want to run, too!") but the younger kid will just sit and chill as long as we're moving. When I had just one I would have to sing and keep up a conversation with him to keep him from jumping out. That's his personality. Playing peek-a-boo games through the transparent top is a tried-and-true game to keep them going. So is playing "Find an X (deer, bus, etc.)" type of game. We would usually go on 1-3 milers. With the new one I can go out on 7 milers. Sidewalks suck, so if we are in a residential neighborhood with scant traffic we will run on the side of the road facing traffic and move to the sidewalk if traffic picks up. Trails are very good.
It's still a good workout. Obviously it's different on your form so that's a downside, but you can still get the kids out of the house and get a workout in. Different kids are going to enjoy the stroller more or less. The kids like to say "faster, daddy!" so I suppose it wouldn't be a bad setup to do a fartlek workout in. Otherwise I would stick with short to medium runs.
One note -- the stroller you linked to has a fixed front wheel, which is fine. They sell a version that has a free front wheel, too, which is really annoying when you are running but very helpful if you have them in, say, a grocery store. If you have the free wheeling stroller, I recommend locking the front wheel when you run.
Oh, the stroller sucks in over 2" of snow, but you probably imagined that. It would work pretty well if you could fit the wheels with skis, though.
Stuff the seat side pockets with toys. We have lost a lot of toys on the trails around here. It's really hard to tell when they disappear if your kid doesn't say anything.