We finished off the Descent: Road to Legend campaign today. Twelve sessions, and we started over a year ago. I'm pretty sure that's the longest campaign (either in sessions, or in time) that I've ever participated in. I think 10th level or bust was only around 8-10 sessions.
Anyway, overall the game was a good experience. The campaign is fun and pretty well put together, and I think everyone gets pretty attached to their characters. It's fun growing the abilities of the characters (and the overlord) at a steady rate, as opposed to the 1st-to-20th level progression you get playing a normal single game of Descent. Also, although the game is obviously much longer, you can break it up into manageable chunks. A successful game of standard Descent usually takes around 5 hours so it's great being able to play for just a few hours and quit when you're starting to fatigue as opposed to a standard game where for the last hour or so, your brain is mush.
The only real downside was we occasionally had some attitude problems. By this I mean, the two other guys playing the campaign are generally good guys, but when the chips were down, they could both have negative attitudes which fed off each other. This was not so great in the Silver level of the campaign, sort of the "Empire Strikes Back" phase of the game, where everything goes against the heroes and they have to work hard not to lose. I was definitely glad to have Enron playing as a balancing factor and to be someone I could always joke around with when the other guys were getting a bit pissy. In many ways it was similar to having Rudy participate in the "Flamer Game" of Basic D&D back in high school.
That said, to be fair this was all of our first time going through this, so nobody really understood that these phases kind of happen and that they don't mean the game is broken or that you can't pull a victory out. And when it came to the final battle against the Overlord, everything really felt like it came together. The battle was pretty lengthy and fairly tactical, and not one-sided. So even though the heroes pulled out a victory, I felt satisfied with the whole experience. I would in fact gladly go through it again!