Another weird thing is the timelimit: I made an offer today and someone accepted and payed 15 minutes later(issued the tx at least). Now the timelimit was set to 20 blocks and I think it took about 24 blocks until the payment was confirmed... So basically I got free bitcoin while the other person payed in a timely manner from his point of view(15 minutes), but due to the nature of complexer transactions, fees and the mercy of miners his transaction got delayed. It was just a tiny amount(0.00012), but if people are unaware of this, it can cause quite some financial damage to them.
This system appears unreliable to me. There should at least be warnings in the wallets/clients if users want to issue/accept an offer with an unreasonable short time limit.