Yeah, Google Music is great when it works. I love how you can use the Instant Mix function on a PC (which works great now, compared to when the service was launched) and it shows up as a playlist on the mobile app (next step: allow creating Instant Mixes on the go).
I do look forward to a more stable version. On both my Photon and my Asus Transformer, it's a bit unreliable--stops playing randomly, doesn't forward to the next song when on shuffle, etc. Still some work to be done, but a nice service overall. Much prefer it to Amazon MP3.