Hussar, I've been looking at Heathen since I started my 4e campaign 2 years ago. If the gang ever get to it now I'm going to have to do a lot of rewriting. (So far all I've done is a variation of the raid on the refugees that opens the adventure.)
How has the initial skill challenge played out for your group?
I'm not DMing, so, all my impressions are on the other side of the screen. The initial skill challenge was BORING. Go to town, make a diplomacy/whatever chatty check, get the info, go to the next town. Wash, rinse repeat. Bleaaahh.
The DM redid the next skill challenge, in the evil town (forget the name sigh) when trying to find information about what was going on with the person we were following (trying to avoid spoilers here). The DM reworked the skill challenge and made it flow very nicely and narratively. Engaged all the players and more than a few different skills. Worked nicely and smoothly.
The fights seem a bit ... wonky. Too much, 1 fight no fight for a week, 1 fight, no fight for a week - too much screwing around to be honest. Fun fights, but, because there's no follow up, you can pretty much guess that you can nova on the fight and blow dailies. The pacing needs work. Less throwaway fights and more focus on what's going on.
If I was rewriting it, based on my very limited knowledge of the module, I think I'd string three or four encounters together, then skip ahead, then string three or four encounters together, instead of the way it's set up with too much time between encounters.