Cons: Plane was empty and the clerk checking me in made me check my bag because it was 3 kilos over their small weight limit. It was certainly not heavy enough to be an issue in storing the suitcase in the overhead bin - even if the plane was full. Plus, it didn't cost me anything to check it, so I don't understand why that was necessary. Instead, I had to repack my belongings because I didn't want to risk damage or theft from having to check my bag. The clerk was so stubborn about following the literal rule, but had no idea why.
Half way through the flight, I could smell really strong cigarette smoke - but no one was sitting around me. I swear someone was smoking, despite the warning and signs. The crew passed by a few times and didn't notice. It was strong enough that I was getting nauseous by the time we landed.