We would give Black Sail five stars even if it was run by Basil Fawlty because of its extraordinary location, deep in the heart of the Lake District with the three great bastions of Pillar, Kirk Fell and Great Gable towering above. It may sound odd to say that a combined trip to the outside loo at 3am with snow on the ground was the highlight, but the utter silence, soft moonlight and great mountains were unforgettable.
The current wardens, Martin and Suzie, have left after two years to bike off to the Middle East in search of adventure (and maybe warmth) but they know their as yet unannounced successors and clearly approve of them. we'd guess, therefore, that when the hostel re-opens in the Spring, the very high standard of friendliness, cooking and wine will be maintained. Over the winter, you can book the whole place for self-catering groups at weekends - check out the YHA website, Escape to.. section.
Don't expect a good night's sleep unless you are very tired or drunk (both of which are quite likely). It's all very small and basic, and when full up, very crowded. The old YHA condition of doing chores has gone but it's much appreciated, and fun, if you pitch in with washing up etc.
We wouldn't stay for more than one night but it's definitely one of the 500 things to do before you die. Going as off-season as possible is best, cos of the legions of Cost-to-Coasters calling in during the day, as mentioned by others. Access from Ennerdale is straightforward if long in all weathers. Scarth Gap and Black Sail passes shouldn't present problems even in mist but be careful if coming from Honister; the moorland at the top of Loft Beck can be very confusing in poor weather (even if you can hear one of the slate mine's JCBs clanking about nearby).
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.