Well I will try to answer since nobody else has yet....
I have both games. It has a similar "feel" to AH. But it is MUCH less complex. You dont have as many "bits" to mess with at all. Setup takes about 5-10 minutes once you get the rules down. So much less then the typical 20+ minute setup on AH.
The difficulty on the default game in my experience is a bit too easy. So its not like AH where in my groups experience it was much harder to win (Id guess we would win 1 out of 4 on AH where on default DN I would say we may win 3-4 out of 5).
If you play with the more "Advanced" rules though the game hits just about right. It actually plays a bit more similar in mechanics to Defenders of the Realm. But less fiddly. You only place one "chit" down per turn in one area...you dont have multiple things to place and spidering effects etc etc.
Fights are resolved fast...abilities are straight forward. My sons and I have played about 8 or 9 games of it now. We like it. I would say its a AH/DotR lite. It plays faster...sets up faster but still has a good challenge and is fun to play.
Or 90 minutes when the Knight just kills every blight that gets in her way (seriously, Saturday night our Knight didn't miss one kill...add that to the Seer getting a 6 on the 1st try on prediction and the Necromancer didn't stand a chance once we got a relic).