It's been roughly a week since I got GarageBand onto my TiBook. Here's some thoughts. First of all...FUN! I have to say that this app has singlehandedly gotten me back into a music making mode that I haven't been since approximately 1985. It's been too long since I've picked up my saxophone or done any recording (I was an audio engineering major at one point) and once you've got the music-making bug, you always have it...apparently.
Although some, like Alwin, have had problems running GarageBand on their rigs, I haven't had any problems doing the basic functions on my 1Ghz TiBook. I admit I haven't tried to create something with more than 7 or so tracks, but I've been able to do everything I wanted so far without being constrained by the horsepower on my computer.
I have gotten over one of my big pre-purchase problems about GarageBand, by figuring out how to get a midi file input into the app. For those of you who, like me, have no keyboarding ability whatsover, you just need to get a basic Midi player (Mighty MIDI works great and is free: http://fenix.wox.org/proj/mm.html). Then, before you launch, go to the Audio Midi Setup (it's in your Applications > Utilities folder), double-click the IAS Driver icon and check off the "Device is active" checkbox. Now, when you launch GarageBand, it'll think there's a Midi device attached and you can playback a midi file using Mighty MIDI that will play in GarageBand.
The other positive side effect of GarageBand is that I now have a sound generator for my WX7 Wind controller. As I said before, this thing has been sitting in my basement/garage for more than 10 years unused, because my brother (the REAL keyboard player/musician in the family) was the owner of of all the synths. What is it? Picture a black stick with keys and a mouthpiece much like a saxophone, but it has a wire coming out the bottom that you plug into a keyboard or other midi-capable sound generator. You blow into it and finger the keys and that makes the sounds come out of your synth. Now I can use GarageBand's "software instruments" as my sound generator, and it's pretty good.
So, what does it all sound like? Here's an example. This one is a downloaded midi file doing the keyboards, bass and strings. GarageBand loops doing the percussion, and Me playing the melody with a guitar sound by using my WX7. I know it's borderline elevator music (ok, maybe not even borderline, but it's MY elevator music!). I'm pretty impressed by how "credible" it all sounds. Let me know what you think.
The Girl from Impanema