They sent me two shipments from the US to Bosnia.
The first one contained a mouse, keyboard, and other small items. The second shipment contained a tablet. No significant problems. I'll continue working with them.
Edit: Since then, I've shipped more packages with them. What's changed is that I'm using a different provider: MyUS. It's much cheaper (cost by weight) and better quality. Although, Planet Express might still be better for some stuff.