Other threads kept me busy but now for the review.
The Black Knight's Boat is not a bad set but not a great set, either.
It's somewhat unbalanced with its massive structure at the prow and the tiny structure at the stern. And I too wonder how this ship is powered? The oars at the stern seem to be the steering.
The over-all design suits the style of the Dragon Knights well, so this is a pro.
DM's con that is only available in a value pack is indeed a con. Mainly because value packs like this have never been available in Gerrmany. However, that challenges the collector's stimulus and could almost be considered a pro :-)
As for the prices at BrickLink: There's a huge difference between prices for used models and prices for MISB sets, in particular if those sets are discontinued for a couple of years. You must not expect to get a MISB 6086 at the same price now as it has been in 1992, unless YOU are the one who picks it up in a dusty old toy store :-)
Though $450 is way too expensive. In principle prices for sets on BrickLink are too high.