Aren't Ghouls CR 2?
I'd say that as described the Bakemono is probably a tougher foe than a CR 1 Gnoll, granting that a Gnoll is a weak CR 1. I'd be very tempted to bump them to CR 1, because they are clearly a very strong CR 1/2 and a worthy foe certainly up to 3rd level and possibily for 4th level characters.
It's bite is by itself nearly as rough as an Orc's Great Axe in terms of likeliness to hit and damage done. Bakemono therefore make a problimatic low level encounter, because the bite is intrinsic to the foe, and the DM can't simply avoid the potential problem as they can with orcs by giving the orcs morning stars or greatclubs to keep the foe reasonablely matched to the party. Add to that the additional two attacks per round and I do see a potential problem. Add to that a suggested AC of 17, and the Bakemono are probably at least as dangerous as 1st level ECL 0 fighters with average h.p. and attributes.
Let's assume average AC for a first level character is around 15, then a full attack from a Bakemono does an average of 4.7 damage per round. Assuming the average attack bonus for 1st level characters is +2 (which is generous), and the average damage 7 (also generous), the PC's are doing on average 2.1 damage each in return. One thing is pretty clear. One on one, Bakemono will wipe out most 1st level PC's. So, three vs. four was probably too much for a first level party. Too much can go wrong. I would do the math as follows. Three Bakemono = 15 h.p. Average survival time = Two rounds. Average Damage Generated in Two rounds = 28 Likelihood of Player Death = Very High. Likelihood of TPK do to early PC death or poor luck = High.
Don't whine about poor tactics without actually knowing how the game was played. Avoiding a full attack by the Bakemono is going to be problamatic if they charge, or otherwise appear at close range, or win initiative. The next round after contact you are faced with the choice of taking an attack of oppurtunity (from the bite!), doing nothing, or facing a full attack the next round. I think personally that taking an AoO from the bite is a worse option than facing the claw sequence of a full attack action.
I do want to point out that even if the CR of the creatures is 1/2, the encounter is above the level of the party. How would the party have fared against only two Bakemono? It sounds like the Party wasn't able to get much use out of the AoO they might have recieved from the Chain and Longspear. Did the Bakemono have surprise or some other factor which made this already dangerous encounter even more deadly?
I also want to point out that if 3rd edition follows 1st edition (I haven't paid much attention to 3rd ed. OA), the OA PC classes are slightly more powerful (especially at low levels) than other core classes, so the designers may have been generous with the abilities of low level foes as well.
