By "fake sounding music", I'm assuming you mean "music that's looped a lot and with effects." I'm not sure if you mean any digital recording of music is "fake sounding music" (vs. live acoustic music).
GarageBand is a tool for recording as much as it is a tool for effects. You don't need to add effects, or mix down your recordings at all. Your end result can be as raw as you want it.
Yes, GarageBand is worth learning. There are many other DAW's worth learning, too, but GarageBand is a great place to start.
For what it's worth, "real musicians" also use GarageBand, so it's not just a place to start, but could be a great place to stay, if you want to:
- Trent Reznor (NIN)
From Trent Reznor:
“For quite some time I’ve been interested in the idea of allowing you the ability to tinker around with my tracks – to create remixes, experiment, embellish or destroy what’s there. . . . What I’m giving you in this file is the actual multi-track audio session for ‘the hand that feeds’ in GarageBand format. . . . Listen. Change the tempo. Add new loops. Chop up the vocals. Turn me into a woman. Replay the guitar. Anything you’d like.”
In fact, Trent encourages you remix NIN work with GarageBand. NINRemixes.com - 0