I used to have for 5 years a backpack from JanSport, which I had paid for 140 euros back then. That was perfect, but it was time to change it, so I bought this one (46 euros at the time of writing). It is a very good backpack with regards to its quality, I can see I'll have it for many years too (and I'm not polite with my backpacks). There's lots of space, which was a requirement, and the protection for the laptop is excellent. That said, I do have two regrets:
1) There are very few small, clever pockets. I was used to having a multitude of them to organize my small stuff, especially when traveling for 1-2 days and would take no other luggage. And,
2) the biggest problem for me, its straps are thinner than I'm used to, so it feels much heavier than my old one. Again, having test-drived a number of backpacks in local stores, this one is better than average in that regard. But, if you're going to fill it up, be ready for some serious strain on your shoulders. I have ended up deciding that it's impossible to get a backpack with really good, thick, convenient straps, unless you pay well more than 100 euros.