How is this better than lighting the candle?

There is no flame, so no smoke, soot or fire risk, and the scent comes out faster because the wax melts from the top down. You also get a dimmer and a timer that a lit wick cannot give you.

Does the dimmer really change the scent strength?

Yes. Lower brightness melts the wax more slowly for a subtle scent; higher brightness releases more fragrance faster. It also doubles as a small dimmable lamp.

What kind of candles does it work with?

Jar candles that fit under the warming head, since the heat comes from above. Taper and pillar candles without a jar are not what it is built for.

How does the timer work?

You set 2, 4 or 8 hours and the lamp shuts itself off when the time runs out. That means you can leave the room or fall asleep without worrying about the candle.

The warmer lamp and a 50W GU10 halogen bulb. You supply the candle.

Will it melt the whole candle?

It melts the top layer of wax, which is where the fragrance is. The wax does not evaporate, so the candle lasts a long time, though the scent fades once the top oils are spent.