I have to add for the OP that the seller should provide a lot more pictures.
Check the current Brain Bag page and ask for the same detailed pictures, especially the zippers (the 3 on the pockets and the top one), the top handle, the straps and the buckles which are extremely tough, (but could have been subjected to a crushing force like a door or the wheel of a golf cart)
I have to use to extreme cases incidents as TB bags are extremely tough.
Additionally a detailed picture of the bottom of the bag is a must, because it takes the brunt of any use, especially the heavy use on outdoor surfaces or student life.
https://www.tombihn.com/collections/...31808802848831
The vintage TB Brain Bag is made of Cordura, which is a fabric that is a pet hair magnet and might be lightly abrasive to knit fabric, which should not be a problem with a backpack, because you have the fabulous breathable mesh and cushioned back.
While the vintage blue label TB Brain Bag has very comfortable straps, the most comfortable I had ever used on a backpack.
The newest version of the Brain Bag has those state of the art Evazote straps, and many slight but noticeable improvements, usually inspired by users over the last 14 years. For example Tom added the very nifty triangle clip to secure a water bottle, a tripod, walking sticks, etc... that is secured by the strap between the two front pockets.
The new fabrics, bluesign

certified 525 denier 2x2 Ballistic nylon exterior lined with bluesign

certified 210 denier 2x2 Ballistic nylon are as soft as they are strong.
If you want to get familiar with the Tom Bihn design philosophy and his strong and good looking designs, go for the bag you saw, unless there are very visible wear and tear.
But, if you can get one of the new Brain Bag, for example, as an holiday gift, go for it.
I own another Brain Bag, which is the next generation after this one, same logo and same fabric, it has many improvements over the grey one. Notably, O-rings in the pockets and a redesigned top handle.
I have been trying to justify a third Brain Bag, but... Tom Bihn and The Designing Crew: mostly Nick and Darcy, sometimes other Crew members, people who work at the factory doing a first class job at making design ideas, into gorgeous bags.
Both my 14 year old bag and the slightly younger one, have been mainstays of my moves (coast to coast, interstate, and local) and all my domestic travels, within the U.S.