I am laying down tracks, making each loop longer by repeating, I am playing with the introduction of loops and fading loops in and out. I like how you can easily isolate tracks to manipulate the volume, then quickly and easily turn the other loops back on to hear what you just did.
I also think that it is amazing how easily the songs are converted and put directly in your iTunes library. I didn't even realize it until I heard one of my songs playing in the car! I had synced my iPod and had it on shuffle when this familiar song came on. I was not expecting it and had a, "wow, technology is really cool" moment.
I did all of the tutorial videos on the Apple website minus the videos that instruct in real instruments or the videos that show you how to record your instruments. For now, I am happy playing with the electronic loops. I think it would be pretty incredible to record your own instrument and mix it with the tracks in Garageband.