Although it was as big a commercial success as Foo Fighters' three previous albums, 2002's One by One seemed flat and tired, as if their leader, Dave Grohl, had reached a songwriting slump or as if the band had exhausted its possibilities. The time was ripe for a reinvention, or at least a risk, and the group responded accordingly with In Your Honor, a double album containing one disc of hard rock and one disc of acoustic material. Splitting music along such a clear dividing line is dangerous: since each disc explores one specific territory, each could sound monochromatic, but instead of falling into this trap, Foo Fighters benefit from these self-imposed constraints. Both the rock and acoustic albums have their own distinct character -- more so than, say, Guns N' Roses' separately released Use Your Illusion's, which felt like one gigantic sprawling album -- and while each is recognizably the work of Foo Fighters, neither feels as formulaic as One by One. While the acoustic album would seem to be the biggest break from tradition -- not only does it have a hushed, subdued mood, but it's filled with guest stars, including several appearances by Led Zeppelin's John Paul Jones, a duet with Norah Jones on "Virginia Moon," and Queens of the Stone Age's Josh Homme returning the favor of Grohl's drumming on Songs for the Deaf by laying down guitar on "Razor" -- both albums showcase a reinvigorated band that is eager to stretch out and experiment. As such, the rock album not only hits much harder than One by One -- arguably, it rocks harder than any of their other records -- but its has fluid musicality and a new found sense of drama that gives it a nearly cinematic sense of scope. Naturally, the acoustic album is quieter, but it also has a similar flow and easy grace that makes it a fitting complement to the harder first record. Previous Foo Fighters albums have had the problem of being a little inconsistent, both in terms of material and in terms of maintaining a consistent sound, but here, perhaps because of the focused direction of the two albums, they not only sustain a consistent mood on each record, but the songs on each are strong, hooky, and memorable. Which mea