I still have one unconfirmed transaction, after 16 hours, and that's a bad surprise, because I had made another transaction which went through in 4 minutes, just one hour earlier.

It is shockingly easy to spam the network. I would have been happy to use a larger fee if I had known something bad was about to happen. Maybe we should add a "unconfirmed transactions backlog checker" on clients to warn us about the state of the network, and invite us to use a larger fee.