With Internet access, you can then play your songs from a browser on a computer, on selected Android devices (which likely provide the best experience), or from a browser on an iOS 4 or higher device: http://www.google.com/support/androidmarket/bin/answer.py?hl=en&answer=1114577&topic=1663424.
Under iOS 5.0.1, I use Safari, which worked best in my testing, and I bookmarked the site in Safari's Reading List, to be shared across any iOS device having my Apple ID. Using Camera Roll on a 4th generation iPod, which includes the possibility of playing video (which includes an audio component, which would naturally compete), stops music that is playing. Some other apps like Mail, which don't have native, primary audio components, could be used without interrupting the music.
I tried two browsers I rarely use, Late Browser Mobile (1.0) and Sleipnir Mobile (1.4.8), to see if they might be repurposed as music-playing apps. They were apparently limited to playing a single song once (continuous play would not work), and unlike Safari, they stopped playing music as soon as you tried to switch to another app (with a double press of the Home button).
With no Passcode set on an iOS device, you can set Auto-Lock to never, which is optimal for using Google Music.
However, if you have a Passcode set on your iPod, the Auto-Lock can be set for at most 5 minutes, severely limiting your options for using Google Music. The maximum analogous iPad option is 15 minutes.
Apparently, Safari must be open in the foreground and the iPod active (i.e., not in sleep mode) for much or all of the time that you are using Google Music in order to play multiple tracks continuously. If the iPod goes to sleep mode, it still loads the next track, but you must wake the iPod to play the track.
If you want to replay the same track continuously, Safari need not be in the foreground, and the track will keep playing even if the iPod goes into sleep mode. Perhaps only folks like me, who years ago recorded the same song continuously on both sides of a cassette tape to play on auto-reverse tape decks, can really enjoy Google Music on an iPod (A version of 茉莉花, plus The Art of Noise's Moments in Love from The Best of the Art of Noise, inspired me to make such tapes.).
I had previously ripped my CDs at 320 kbps (highest quality) onto my PC, primarily for use with my Microsoft Zune. The Zune provided a very helpful introduction to podcasts and mp3 usage, but I use it less and less over time. The ripping process for those CDs was long and laborious. Not particularly needing music on my iPod, I never felt like repeating it for PC iTunes, or cared enough to look into how to make those mp3 files usable in PC iTunes (particularly if such required making another copy of each song for PC iTunes). Google's Music Manager allows me to leverage my existing mp3 library with a bulk upload operation for use with my iOS devices. With my slow Internet access, it took me about two weeks (mostly overnight) to upload around 3200 songs and podcasts.
If you lost all the media (e.g., iOS device, personal computer, CDs) on which you have your music collection (e.g., because of a natural disaster), your Google Music backup should still be available. The rules (as of 12/5/11, anyway) allow you to download 320 kbps mp3 files of your music: http://www.google.com/support/androidmarket/bin/answer.py?&answer=1701736. I load only some of my songs onto my iPod, but upload all of them to Google Music as a remote backup, and for occasional web browser listening.
The iPod speaker can be fairly tinny sounding, but I am not a serious connoisseur of audio quality. I generally don't like wearing earbuds, so any time I can reasonably listen to stuff without them is good with me.
My slow Internet access could be a significant factor for some of the following symptoms which I experienced on an iPod or on an iPad:
- There is a delay before each streamed track begins.
- A track might not initially start playing. Hitting pause and/or play sometimes starts it playing.
- A track might abruptly stop playing. Sometimes it will restart by itself.
- When playing multiple tracks, a track might abruptly stop playing, and the next track might start.
- If you switch from playing one track to playing another (in my experience, switching between tracks of different artists), the album artwork display may get updated before the streamed track, such that hitting play for the second track actually plays the first track. Hitting pause, then play, corrected that.
Even with better wireless Internet access than I normally have, it's really seemed like if you want to hear one song play all the way through on an iPod, you have a decent but not 100% guaranteed shot at that, and your chances get worse if you want more than that. Google Music is okay with me since I rarely have a particular need to listen to music on my iPod, but it may not be worth the effort for many folks. (Soon after writing this blog entry, I was obliged to get a new iPod, one whose port actually worked normally. I quickly enough discovered how nice it was to listen to music stored locally on the iPod, and Google Music became rather less significant to my iPod use.)