This pack is nice, but does have one pretty big flaw. 12L sounds like a decent enough amount of space for a light pack, but upon usage, comes up short. After you fill your reservoir, there is little room for much else save maybe arm & leg warmers. Getting a vest and shell in here too is tough. Another minor annoyance is that, for me at least, the water line from the reservoir is just a little too short making it more uncomfortable to drink than I'd like.
Great pack, just not enough space for this size pack. Go for the 16L at least.