It seems to be used quite a bit, by mostly a niche (large) group of 'regular' posters, that are routinely active on the boards, whether they have a cruise currently booked or not. IMO there is still a lot of useful information to be found here, if one steers away from the 'hot button' topics like proper dining room attire, smoking onboard (especially in the casino), tipping, to name a few.
I've found the roll calls on the HAL boards to typically be less active than other lines, but some are more active than others.
All that said, if you're looking for helpful information, or have particular questions about HAL, you've come to the right place!