My party of six level 3 characters just fought Nughoak and three hyenas in The Distraction and barely survived it. I added the hyenas because the text mentioned an unspecified number of hyenas charging the characters. Nughoak escaped with 6 hp left. The main problem was that Nughoak managed to cast Darkness on himself, negating the party's Light spell they had cast on a stone. The effect was the he was fighting in Darkness, while they were fighting in a pitch-black cavern.
Nughoak: 20% miss chance.
Party: 50% miss chance, no Dex bonus to AC, and additional -2 to AC, moving at half speed, no line of sight and thus no spells requiring a line of sight such as Magic Missiles.
This basically condemned the Enchanter and the Sorcerer to stand by idly, and the Monk had been standing guard at the top of the rope and took more than ten rounds to come down.
It was tough. I cannot imagine what would have happened if only four characters attempted the fight, and Nughoak had attacked when half the party was still climbing down the rope.
Regarding the stats: I felt that Nughoak should have AC 19 (+1 natural, +3 studded leather, +3 magic shield) instead of AC 20.
Afterwards my party commented on the lack of warning. I guess I should allowed them a listen check to hear Nughoak casting Bull Strenth; I'm not sure.