Are recirculation extractor hoods good?
If you have a gas stove, you need a hood to send the exhaust outside. One that recirculates is not sufficient.

In my experience, the recirculator hoods work OK if you're not doing a lot of cooking. If you do, however, you'll end up with a nasty, greasy dusty coating on everything in your kitchen. I wouldn't bother with a recirculation hood if you ever cook things that involve grease or smoke. For someone who mostly heats up processed foods, it's probably good enough.