Oh, forgot a couple of details.
For take-off and landing, the cabin crew will give you a seat belt loop that goes through your seat belt and then around the baby. The baby has to be in your lap and so belted in for takeoff and landing.
The bassinet solution means you only buy your seat. Children under, I think 2 or 3 or so, travel for free but they have to be on your lap.
It's not as inconvenient as it all sounds. For short sectors, having the baby in your lap isn't really that much of a problem and, on long sectors, having the baby in the bassinet is actually a godsend. Ours slept almost all the way from London to Sao Paulo but, when she did need handling, getting her in and out of the bassinet was far easier than trying to get her in and our of a carseat.
The best baby-survival tip I ever saw was the dad who, when both he and his wife tried half-heartedly for a half hour to quiet their spoiled, hollering, tantrumming 3 year old, stood up, extracted a small box out of the overhead bin, opened it, and then proceeded to offer everyone around them a set of foam earplugs. That act alone not only cracked us all up but also relieved the tension caused by 20 or so passengers getting really annoyed because Mom and Dad seemed oblivious, or unable to control, their screaming kid. Both parents were useless at controlling the kid, but at least Dad was under no illusions about his darling little monster.