Lack of transaction reversals
How is this a bad thing? Bitcoins are not like credit cards, you don't have to give out sensitive data to make a transaction.
I've heard of a dozen stories about merchants going out of business simply because of chargeback fraud, it is a problem that everyone seems to ignore. Imagine that you sell digital goods such as CD keys and some dude across the globe does a chargeback after he used the CD key, good luck getting your money.
Well, if you buy something that then you don't end liking and what a refund, that's a problem.
If you buy something that you don't end up liking, that's your fault. Reviews exist for this kind of thing. You shouldn't get a refund.
Charge-backs shouldn't really exist. It is way to easy to conduct fraud with the system, and rszibele makes a good point, businesses can easily go out of business due to people cheating the system.
Transaction reversals are not necessarily a good thing. The only time I could see a scenario where charge-backs would be useful would be if there was verifiable theft, but then you probably should have taken better safety precautions.