I've a big 15.6" laptop that fits ok (see my pictures up top). Laptop protection is scarce though. Now that I've seen some other laptop backpacks in work, it really shows up how little padding this bag has for my laptop. You can't just let the bag down without thinking, more like gently placing it down and constantly carrying with care. Fitting some dense foam down the bottom of the bag might help overall here.
Stitching seems ok. Some fabric fraying seen already though on the shoulder straps after only 3 weeks. The zips are sturdy, and the straps are a big decent size. Not much water protection I'd say. I wouldn't fancy testing it in a downpour. Comes with a lifetime warranty and the basic styling is actually quite appealling, not in-your-face-fancy.
Overall - not a bad cheap bag. But 'the ultimate protection' - this in not. Treat delicately!
For everyday use, pay more and buy something decent to protect your laptop. If like myself, only using it the odd time, it's fine.