I have had the pack for about a month and have used it for three separate snowboard trips and a bike ride, have generally enjoyed it.
Setup is very easy to use with a convenient pouch on the left strap for your MP3 player, which will fit a regular sized iPod, probably not a Zune or full-sized Zen. However, I do recommend leaving your hard-disk based player at home and buying a cheaper, flash-based player for this activity due to all the snow, potential impacts, temperature extremes, etc. Four AA batteries are stashed in the back of the pack and lasted for two all-day outings at a good volume. There is also a place for your player in the back of the pack which is less convenient but probably a better option for an expensive MP3 player. Also, I did not test the phone interpoperability function, because my Blackberry phone will not answer automatically answer when calls are received.
As I said, setup is easy, you drop the player in the pouch, pull out a plug cord from a hidey-hole in the left arm strap and into the pouch via a reasonably snow-proof zipper setup. The power and volume controls on the right are are hard to see when strapped in and you are often turning the volume up and down by feel, which is fine in spring conditions when you aren't wearing your thickest pair of gloves. Otherwise, you may have to set it and forget it volume-wise.
Sound quality is pretty good, got lots of positive comments from lift operators and strangers sitting on the lift with me. The sound carries, so be careful of the offensive lyrics around the kids and easily offended. You are never going to get a ton of base out of 1" x 2" speakers, but I found the sound sufficiently inspiring to cause me to risk life and limb on the steeps. The one complaint would be a fair amount of distortion with certain tracks with lots of base, you may want to play with equalizer settings a bit. I found "Show Me How To Live" by Audioslave to be quite distorted, but I was rocking out and most songs were fine.
The only complaint I had is that on two occasions the sound acted up on me. Once on the slopes, the sound just stopped even thought power, batteries and connection were fine. I powered down for a few minutes, restarted and it worked fine. The other while on a bike ride, I started getting intermittent sound even thought the MP3 player was fine. I couldn't fix it at the time but could not replicate the problem later either.
Camelback features were great, drinking tube was insulated and I like the new bite valve.
So in short, really enjoying the thing but keeping my receipt handy in case I encounter any more problems. On balance, I would say take the plunge if you want to have your personal soundtrack with you but still be able to hear people around you.

This is 1 well thought out pack,everything is so accessible. Extremely well made. I am positive this pack can servive the war over in Iraq. I own 3 other Camelback packs and like them as well, but this is my most used one now. I take it just about everywhere I go. Hiking, cross country bike riding and back and forth to Colledge. I had to get the adapter for my Razr cell phone from Skull Candy and they did not charge me and shipped it UPS. It arrived in 2 days. The service was exceptional. I think I might order another one to give to my nephew. He just LOVES it.

I bought this pack 3 weeks ago for everyday boarding and let me say its fantastic. The speakers are loud and clear and absolutely audible at full speed. The handy controls let you turn down the music when getting warned by patrols, and the pack is big enough to carry anything. My hydration hose froze the first day out - but I'm pretty sure that was user error.

This is the best thing to happen to packs since hydration. I like the fact that I can listen to my tunes and still be aware of what is going on around me. I hardly ever skied resorts with a backpack. Now I don't go with out it. Skull Candy rules....