It's been like a fricken month (not even). They're Energizer, so it's not like the batteries are from the dollar store.
Okay, so that guitar is sometimes played on expert level for six hours at a time. Big deal. The original guitar from the PS3 Guitar Hero III set has only had its batteries changed once since I got it (and that guitar has played more than Max Tucker).
I'm just saying. Judging from its energy usage, this guitar wasn't designed with battery longevity in mind. Which sucks balls.