I'm not an audiophile, but I do appreciate a good "system". I'm one of those that when I was 16, I got the aftermarket CD player, the subwoofers in the custom box, the tweeters, upgraded the door speakers..etc etc.
The upgraded sound system was a "no brainer" for me as I am in the car a lot, and I listen to music a lot. With Slacker, you'll find yourself listening to even more music. I don't have the time or motivation to to load thousands of songs onto a USB, but with Slacker its awesome to just listen to the "radio station" for one of your favorite bands and listen to music from bands you've never heard of. Then it's always fun to say, "Play *song I loved when I was 16 and rocked out*"...turn it up and just rock down the road. With the upgraded sound, I messed with the settings (bass, treble, mid range) until it sounded right and it's awesome. You can feel the subs in the door panels vibrating your knee.
I've had to reset my main panel a few times and evidently that resets the customized sound levels, but I didn't realize it at the time. I noticed I was a little let down in some songs where I thought there would be more "presence". I discovered this morning that all of those presets had reset back to "0". So after setting them back to my liking....WOW....it without question, made me glad I got the upgraded sound.