Those no-name ebay packs are not very terribly. I carried one for a week, and there were a few tears (mostly cosmetic). I only stopped carrying it because it was too big, and I sewed the straps onto a different bag.
It is a good price, but if you're hard on your gear, don't expect it to last forever.
I bought one of thse about two years ago, and it was the biggest pieces of shit i ever fucking used. you could almost see through the material it was made of. You always get what you pay for, save up and buy a good pack.
yeah, i'm sportin an alice right now and figure anything would be better than it when it comes to comfort. But yeah durability was what i was mainly concerned about with these.