Blame it on Apple\u2019s non-negotiable 30 percent commission, but Google Play Music, now available as a free iPhone\/iPod touch app, is missing two crucial features: the ability to shop for and purchase music; and to sign up for its $10\/monthly All Access Plan. (You can do both using Google Play Music on an Android device or through the Google Play Music website in any browser, including the iOS Safari.)\n\tYou can\u2019t even sample tunes in the iOS app. In fact, if you\u2019ve never purchased music from Google before, the Google Play Music app on iOS, once installed, will be completely empty. It\u2019s an odd experience \u2014 like showing up at a party with no one else there.\n\tNot surprisingly, Google wouldn\u2019t want to give its competitor Apple a 30 percent cut on every track it sells via iOS. And to be fair, you can\u2019t buy songs through the Amazon Cloud Player iOS app, either. You can, or course, use a browser to purchase content in both Google's and Amazon's stores and then listen via the iOS apps.\n\tDepending upon your perspective, this is either an advantage or a disadvantage. If you\u2019re the type who frequently and impulsively buys songs after the usual 30-second iTunes sample and then sometimes regrets it, Google Play Music\u2019s lack of e-commerce impulsivity might be a good thing. On the other hand, having to open up a browser to purchase a song can be a turnoff.\n\tI fall into the latter camp. So I doubt I\u2019ll be a big Google Play Music user.\n\tSo who\u2019s the real target user? If you\u2019re an Android owner who\u2019s purchased lots of tracks from Google but want to switch to iOS, Google Play Music is what you\u2019ve been waiting for.\n\tGoogle Play Music for iPhone\/iPod touch has other benefits compared to its closest competitors iTunes\/iTunes Radio and Amazon Cloud Player. If you subscribe to the All Access service, you get about 20 million songs you can either stream or download (at no extra cost) to your iDevice. (FYI, iTunes has more than 28 million songs, and Amazon\u2019s music service also has about 20 million.) Once you end your subscription, of course, the songs vanish from your device. The advantage: Using Google Play Music, you can download lots of songs and play them to your heart's content, without actually having to purchase them or stream them. With iTunes Radio in the iOS Music App, you either stream the music\u2014which can put a hit on your cellular carrier's data plan, if you listen to music while exercising outside\u2014or you buy the songs outright.\u00a0\n\tWith All Access, Google algorithms help you discover new music you might like, based on music you own and listen to. You can make playlists or listen to those created by Google music experts. But other services do this as well.\n\tI like the look of Google Play Music, and it\u2019s easy to use. But the iOS app made me feel like a visitor to another land \u2014 with a restricted pass.