The consequence of Tom Petty and the Heartbreakers' enduring affection for the music of the mid-'60s was that, in essence, they were a singles band, a fact driven home on the first three CDs of the six-disc set Playback; even when abbreviating each of their first nine studio albums to four to six cuts, the songs break down into the hits and the also-rans. To be fair, there are quite a few of the former, and some of the latter are could-have-beens; and since Petty is more a song maker (or, more precisely, a track cutter) than an album artist, his work is more amenable to compilation...Then come three more discs of rarities and outtakes. The first of these contains non-LP B-sides, most of which are pleasant throwaways (although "Trailer" suggests that the failed concept album Southern Accents could have been more of a success if it had been included). The last two discs present early and alternate histories of Petty, as his pre-Heartbreakers group, Mudcrutch, searches for a sound; later, he tries out different approaches that never made it onto his regular albums. Some of this material will be of interest to hardcore fans... ~ William Ruhlmann, All Music Guide