The newer Porter 30 is a couple notches up from my other Ospreys (Hikelite, Daylite, Daylite Plus, Veer messenger bag). It could be used daily but it best meets my carry-on travel needs. It gives pride in ownership and looks fantastic. The material is a very strong ripstop and the zippers, buckles, waist strap, hip pads, and handles are all a couple notches better than my other Osprey packs. The admin section is a bright green and the zip areas for shades and traveling docs along with a separate zipped area now for a laptop and an iPad are done well. There is no water bottle slot or internal compression straps though. I use a case but that non-scratch material would have been better for the shades pouch, too. Its also comfortable to wear for jaunts through airports and off to hotels and such but I wish Osprey had added some back panel breathable improvements. Its just a flat back now and air can’t escape.The Castle grey is a dark greenish grey & very classy color. It is smaller looking than I expected (a good thing) and still holds a week or two of my gear when I pack correctly. Another 5 liters or so would have been better for me though.You can cinch down any day pack, jacket, or anything that you want on the Porter because of the fabulous straight jacket compression. You don't have to use a Daylite or other Osprey "compatible" pack. I included a few pictures with the Osprey Hikelite 26, Camelback mule, Osprey Daylite plus and a Thule 21L and all secure well. This Thule is perfect for traveling with the Porter because it has a great 'crush zone' pouch on top for shades, passport, wallet and cell. It also has a slim profile, a side slot or the stuff pouch for a water bottle, attaches/detaches quickly, & looks sharp cradled in the straight jacket.It fits under the seat but this takes away a lot of leg room so I recommend using the overhead bin for comfort. I just detach my daypack & store it under the seat in front of me (with valuables and flying gear). The Porter has great handles & stores like a small pack on its side in the bins (like a book on a shelf) so you likely can fit it in a bin that was even closed already. I love that! I included a pic below of my Thule 21L strapped on the Porter from the side profile. I don’t like the shoulder strap option because it’s not how I would carry in an airport and also because Osprey doesn’t include a shoulder strap.Be prepared for compliments and questions from other travelers on this beauty. It is so close to perfection as a carry-on bag/backpack now. Hey Osprey, add a water bottle slot, internal compression straps, make the hip belt removable, add an air channel up the back for breathing better, add a 'secret' zippered pocket on the back for a passport, and add an expandable 3-5 liter zip out option (like on the Vaude Wizard) and this will be the greatest carry-on ever!P.S. on packaging: The Porter 30 came very fast and packaged to perfection in its Amazon box. It was in a perfect sized box & had air pillows placed strategically around it. You could tell it was held in high regard by the people who put this packaging together. Much appreciated and thanks for the big wow factor when opening the box!P.S. #2...I recently picked up an Osprey Tropos 32 and that is much better than the Porter for a lot of tasks including travel/carry-on. I'll do a review on that one soon but its not even close as the Tropos is much more travel friendly, has a superb breathable back, better organization, and a freank'n kickstand! Yeah, a kickstand! No more struggling with a carry-on during those long airport lines for me with the Tropos.