The majority of active users here often state that NDPs are not a good value either because you don't know what you are getting, they are overpriced, are repackaged versions of other house brands, are sub-standard barrels from known distilleries, or some combination of those reasons. On the other hand, the most coveted bottles in the bourbon/rye world seem to be from NDPs (PVW, Rathskeller, VWFRR, Willett, Hirsch, Black Maple Hill, Red Hook, etc.) The most confusing to me is Willett. It seems like most members really love Willett, but will knock Rowan's Creek, Noah's Mill, and other offerings from the same NDP (KBD.)
If I didn't know any better I would say that it has to do with the rarity of the bottle more than anything else. What do you guys think?