I have gone through several small backpack-style bags and have shopped all over looking for a good quality and certain size bag as this one. This is definitely that best made bag I have found. When I got it I was so excited. Well, for one, I didn't pay for extra shipping and they fed exed it and I got it in two days. Wow. I was surprised and so happy.
  The bag is very nice quality leather, the interior is nice quality too. I've had many bags where the inside lining was very thin and cheaply put together. Not so with this bag. It is top notch quality. The zipper pulls are even nice looking. Someone wrote that the zippers stick a little but it's not a big deal. I agree with that. It mostly sticks a little on the side pockets, but it sticks very little . Just don't yank it, and it'll probably be fine.
  This bag looks like it will last me forever and can even take a bit of a beating. I need something like that because I can be a bit rough on my bags.
  As for size. Lets start with "roomy". The side pockets are large enough to easily put a water bottle in it. I didn't think it would be by the picture and I think someone said they aren't big enough. But not so. I have a 20 ounce nalgene water bottle that I use alot and it fits in the side pocket very nicely. This will be wonderful for the days I go hiking. I'm also using the other side pocket for a small bottle of excedrin, eye glass wipes, a candy bar, and inhaler. I can probably get my 3rd generation ipod in there too.
  The main compartment has an inner zipper compartment too. Not very big, but it's a standard size one for this size bag. It's adequate to say the least. I put a few travel size packs of tissues in it.
  The big compartment itself is currrently holding my color nook and two paperback books with a little more room to spare. I can also stick an extra drink in there too if I want. This is because the bag is wide enough to hold my nook and a couple books. It leaves enough space, width-wise, to put a 20 ounce drink in it alongside my nook and books. I was pleasantly surprised by this. I'm sure if I remove one of my books I can put a t-shirt in it, or a sandwich and a bottle of soda, or some snacks. My nook goes with me everywhere, so it was important for me to find something big enough for my nook, but not too big. And big enough to hold my nook as well as other stuff. I leave for work around 6 AM and don't get back until 5 PM. I have a driving job and am on the road a lot so I like to take something not too big, but big enough for these items. I also like to take walks on my break and this is another reason I didn't want something too big.
  As for the smaller outside compartment in the front. I can easily throw my wallet in it, headphones, ipod, several pens ( has pen holders built in for two pens ), gum, nail clipper and file, and a few other small items. This compartment isn't as big as I thought it would be. But it's big enough.
  If you carry alot of random items like I do, and want to keep it organized, then this bag will do nicely.