The mass-marketed pop music compilation has come a long way since the days of 12-track K-Tel vinyl collections like Dimensions and Hit Express. Once a useful tool for listeners who just wanted to rock out to Styx's "Mr. Roboto" without committing to all of Kilroy Was Here, the modern comp has become a sort of disposable iPod for the MP3 generation, providing hours of music for a very reasonable amount of money. The That's What I Call a No. 1 installment of the hugely successful Now That's What I Call Music! series is the perfect example. At 60 tracks spread over three discs, and spanning six decades, it's hard to argue with the quantity, but despite the fact that each and every song found its way to the top of the charts at one time or another, the whole thing feels a little lopsided. Sixty years is an awfully big chunk of time to encapsulate, and while the compilers did manage to hit on every decade, they seem to have only found the last two to their liking. Discs one and two are stocked with the usual suspects (Adele, Katy Perry, All Saints, Robbie Williams, Coldplay), with the occasional Blondie, George Michael, or Gloria Gaynor cut thrown in for good measure, while disc three is relegated to the "oldies." Admittedly, it is fun to hear Ian Dury & the Blockheads' "Hit Me with Your Rhythm Stick" just six tracks away from Louis Armstrong's "What a Wonderful World," but really, the third act just feels like an afterthought.