Just got back from the show. If you're thinking if you should go or not (like I did), definitely go. Being familiar with the material helps, but turned out not to be necessary—I didn't remember much from the first album aside from a few songs and still had fun.
Fiddler on the Green is the damnedest song live. It's even better without a fadeout, and a great show closer. Dorian (which we also got as the second encore) is not the damnedest song live and not a great show closer, but it helped that the second encore was much more spontaneous than the first. The band took a bow, took a picture with the fans, Jon and Frederik threw the picks and drumsticks to the crowd, everyone seemed ready to leave and I thought we won't get it. So I guess it worked as a spontaneous encore, just an additional song played, whereas the "true" closer was Fiddler.
Other two highlights of the show in regards to D&W original material were Love's Tragedy Asunder (figures, I love that song) and surprisingly Terror Train. Welcome to Dying and Valhalla are always a treat, and I liked Burning Times a lot, even though I wasn't too familiar with that song at all (I only knew when to scream "YOU ARE A SINNER!" so there's that).
The biggest bummer is that I got to the venue quite late (the opening band just finished playing) and all the merch was already gone.
No CDs, no vinyls, no T-shirts, only two types of fridge magnets (and I've bought the last one of one type, haha). While I thought it was a possibility I'll miss out on the T-shirt, I didn't think all the CDs would be gone. I was actually looking forward to buying the new remasters, even had some money put aside for that. Oh well.