Apart from visiting the shop and museum, I've only been to one event in NEH and thar was Dirty DC (ACDC tribute act) and enjoyed it.
Excellent venue for a concert, sound system as good as any other venue I've seen gigs in. I don't drink, nut mate I was with said the lager as decent price and decent pint (other than bring served in a plastic cup).
I think the venue is criminally under-used and under-utilised. Needs more gigs and maybe RSC could use it for functions. Centrally needs to attract more events if its to pay for itself at £1m per year.