After searching for a solid, sleek (and leather) backpack for my travels (and one that could easily hook onto my suitcase) I ditched the Tumi dream and instead went for the ISM bag. I have not looked back. The ISM backpack comes in at a fraction of the price, and ~10 countries later it still looks brand new.
Personally, I'm not in love with the blue interior accents. I'm a monochrome type, but realistically I hardly ever notice it. The interior space is actually a bit deceptive and can hold more than it looks, but bear in mind it's still a very narrow body. I can take my 13" laptop, iPad, mouse and mousepad in the zippered slot, and still have room for a 140oz water bottle and my plane toiletries. Throw a small sweater in, and that's about it...but realistically all you need for a flight. Depending on the day, I either love or loathe the fact that I can't buy $34 airport candy. 100% worth the purchase.