I'm a Pacsafe convert.
I got this backpack after almost becoming a victim of theft last winter in London.
I looked online for the best anti-theft brand and I stumbled onto PacSafe. I'm so happy I did. This backpack is big enough to function as my day-to-day backpack. It has just enough compartments and space to fit my tablets and even a windbreaker. It's light, which was a big concern for me. Its water proof-ish. And my favourite thing is the compartment right against my back that I can use for easy access to my phone. I also love that the zipper for the main compartment is also against my back. So even if I don't full engage the zipper tab to the lock mechanism, I still feel that my stuff is safe because to even get at it, someone would have to reach against my back (which I would feel) and fully unzip it around my back (which would be next to impossible for me not to notice when wearing). The only downside I can see is that the backpack is not the most stylish in the world.
I gush about this bag to family because, more than anything, it has afforded me peace of mind when travelling to high theft zones. Additionally, my sister was so impressed with this bag that she's become a Pacsafe convert too and is looking for an anti-theft work backpack as well for her daily commutes.
I am very happy with my purchase.