Let's start with the ugly part first: 12 vermin RHD. Oof.
Stats-wise the beetle follows the typical pattern of melee bruisers. Large size, 26 strength, 23 constitution, all other stats 10 or nonexistent. 50 ft. land speed is pretty good, 10 ft. burrow is reserved for utility. +15 natural armor is quite impressive, even when compared to magic (as in: strictly +X enchantment) armor. They possess two natural claw attacks (which they can Rend with) and a weaker bite.
Like every good D&D monster, the knell beetle gets a bunch of random and vaguely-related abilities. Shake The Earth, while poetically-named, is weak: spending a standard action on knocking creatures prone isn't worth it. Sonic Chime is 1/day AoE blasting: not great, but not useless either. Finally there's Trample (has anyone ever trampled and not regretted it?) and Sonic Healing (which strangely heals 1 HP per 5 points of damage, rather than the typical 3).
The knell beetle's ton of bonus feats do nothing to redeem it. -0 LA.
Lesser Knell Beetle
6 RHD, but much worse stats. Another -0, maaaaaybe +0.