Eh, they hit hard, and that howl is annoying, but they do go down in a handful of blows. For the Devs: Is XP decided based on a calculation of their abilities or is it possible to just give it any number of XP?
Honestly, I'd fight mobats all day and get crap xp, than face off against a pushover like a rust monster any day with my higher levels. Sometimes CR, XP, and the monster don't adequately correlate to what you are facing.