To begin, Osprey is a great company. I received my Tempest 30 after sending in my 2011 Comet for repairs. They were unable to fix my old pack, but sent me the new one free of charge, and had no problem changing the model of the pack.
The pack itself is also great. My favorite part is the hip belts. They fit close and tight. The pack is more narrow than unisex or men's packs, so there isn't extra space between my hips and where the hipbelts attach to the pack. While there is plenty of space inside the pack, it's tall. The result is that the pack doesn't stick out too far from your body, which is a plus if you do a lot of bouldering/squeezing through tight places.
My only criticism is that there's no organization in the main pocket. My old Comet had a laptop sleeve, which I used for a variety of things besides laptops. When you pack a lot into the bag it can be difficult to get to the stuff at the bottom. Pack smart, and you're good to go.
UPDATE: I've now had this pack for 6 months and use it daily. I bring this pack to work on my daily commute, and also take it hiking and traveling. As a daily commute bag, it's a little larger than what I really need. If you're looking to use it for that purpose, I'd look at the Tempest 20. If you're looking for day hike/overnight trips, it's perfect. I play ultimate frisbee and take this bag to the fields with me. Fits multiple layers, rain clothes, growler sized water bottle, cleats, frisbee, dog food, snacks, and is comfortable to carry. As another reviewer mentioned, no rain cover is a downside, but it's easy to purchase one. Personally I steal the rain cover from my Gregory pack and call it good. Still a great purchase, and everything is holding up well!